Is "see" the same thing as "line of sight?"

[Bareheaded Warrior]

If there's a line of monsters down the corridor and the more powerful Dread Warrior is muddled in the middle. If I think the Wizard can see him, I'll allow him to cast Genie. But at the same time, if a hero wants to fire a Crossbow at him, there would probably be way too many monsters blocking the path of the arrow. Not that anyone asked me. But if you play your game differently from mine, I'll respect the rules of your table.

As I've said it is clear that players of the game are welcome and indeed encouraged to house rule at their own table, I'm just trying to get a clear picture of how the official rules (initially just the original editions - 1st and 2nd) are actually supposed to work, before I decide to apply any house rules on top of them.

Assuming from your example above that Genie requires a clear LOS (and this may vary between editions), then you would have different LOS rules for targetting with a spell than you would for targetting with a crossbow, which is absolutely fine at your table but isn't the way the official rules work.

So all 3 ways are consistent:

1) Always use LOS when revealing
2) Reveal the complete area when a hero enters a new room or passage, opening a door requires to move through it
3) Reveal the complete area when the hero reaches a square adjacent to the new passage, or when opening a door, without moving through

Except they aren't, imagine a door placed in the bottom wall of the centre room, on the furthest square to the left. From the square in the passage outside the room you open the door. If you use (1) then a monster in the bottom right corner of the room would NOT be placed as there is no LOS, if you use (2) or (3) then it would be placed, so not consistent.

Except that the rules never use "by moving onto" in any other context than opening doors. Saying that the "Opening Doors" rule requires moving through the door stretches the text a bit too far, I would say. "You can open a door by moving onto the square in front of it." In front means on the hero's side of the door, or does it? "By moving onto" doesn't state a prerequisite for opening the door, but the action that is required to open the door. To me this rule sounds like you are not automatically moved through the door. And should you really get 1 movement square for free just because you opened a door? Hard to believe.

I think that moving onto the square in front of the door, is a pre-condition of opening the door, because you can't open a door without having moved onto the square in front of it (therefore logically it must be a pre-condition), but it cannot be the "action" that is required to open the door because the text clearly states that even if you move onto the square in front of the door, then opening the door is optional, so you can move onto the square in front of the door and not open it, so moving onto the square in front of the door cannot be the cause of the door opening, therefore it must be a pre-condition only.

Moving through the door onto the square "behind" the door is the effect that results from the "action" of opening the door, first the pre-condition by moving onto the square in front of the door, and then declaring that you wish to open the door (the cause), then the effect follows. It doesn't count as a "move" which is clarified by the wording "opening doors does not count as a move" otherwise players may assume it does cost a point of movement, and the fact that this movement is free is a necessary rule, without it you'd have a situation where you wouldn't be able to move onto a square in front of the door with your last point of movement and then choose to open the door. It isn't the only example of "a free point of movement", you could just as easily argue "And should you really get 1 movement square for free just because a block fell onto your square? Hard to believe." Believe it or not that is the rule.

In fact, instead of this point-by-point back and forth, let me try a different approach

And now for something completely different

Note: Ignore visibility in terms of targeting and just consider visibility in terms of placement

Imagine that we are adventurers, negotiating the most perilous and challenging dungeon of all, the rulebook!

1st Encounter

First we encounter a paired set of rules

If in the same room everything is visible to you, if not in the same room then use LOS (ignoring figures) to determine what is visible to you.

At first glance these appear fine, simple and complete because logically between the pair everything is covered, things are either in the same room or they aren't.

The Fork

However we next encounter the "opening doors" situation where the rules hint at the fact that something may be different here, but don't clearly explain it. Our path here forks, for now let us take the left hand path.

Left Hand Path

We take the path that introduces this rule

When opening a door, everything in the room or passage beyond is visible and placed on the board, as if you have moved onto the square behind the door" but note you haven't actually moved.

All good, except when you consider the Barbarian in a room moving in front of a closed door beyond which lies a new room or new passage, he opens the door, everything is laid out, but he decides instead to stay in the room and poke through a chest elsewhere in the same room. Next in turn is the Dwarf, he moves onto the exact same square in front of the now open door that the Barbarian was occupying only moments ago, logically he MUST be able to see exactly what the Barbarian could see moments before from the exact same square, except he can't because the opening door rule doesn't apply (as he isn't opening the door, it is already open) and he isn't in the room behind the door, so only LOS applies.

At this point we revisit our new rule and realise that actually the "when opening a door" condition is irrelevant, the rule needs to apply whether you are opening a door and looking through, or just looking through an already opened door. So we have another attempt

Everything in a room or passage is visible and placed on the board, provided that you are on a square next to the room or passage

Note: the reverse must also be true, that you can be seen by everything in the room or passage, if you are on a square next to the room or passage

This gives us three rules in play, our first encountered pair

If in the same room everything is visible to you, if not in the same room then use LOS (ignoring figures) to determine what is visible to you.

and our newcomer

Everything in a room or passage is visible and placed on the board, provided that you are on a square next to the room or passage

This is the way that I have played the game since 1990 when I converted from 1st to 2nd edition (excluding various house rules), and it works, but I was always a little uncomfortable because this "newcomer" rule didn't appear to exist in the rulebook, so it felt to me like the rules as written were incomplete and I had to create a house rule (no problem with this but I would have liked the rules as written to work)

I would reveal the whole army when a hero steps on B. With "place only when entering a new passage rule" you would reveal all when they reach C, which feels strange. With LOS you would reveal the left Fimir when they reach A, the right Fimir and the lower left Orc when they reach B, and the rest when they reach C. This reminds me of old computer games where you could trigger enemies one by one by carefully stepping forward. It feels like a hack from the players.

In the example that you gave earlier this would leave us in a situation where the left Fimir would be revealed when a character moves onto square A, due to the LOS aspect, the "whole army" would be placed when a character moves onto square B.

Note: Your option of ignoring the LOS rule (the placement when a character moves onto square A), introduces a whole new complication, a modified version of the rule "if not in the same room then use LOS (ignoring figures) to determine what is visible to you" would have to be created along the lines of "if not in the same room then use LOS (ignoring figures) to determine what is visible to you unless you are on a square that is next to a square that is next to a passage in which case you ignore this rule specifically in relation to things that are in a new passage (insert "new passage" definition here)"

Right Hand Path

But for a moment let us return to the fork and explore the other path.

This path we still have our first encountered paired set of rules

If in the same room everything is visible to you, if not in the same room then use LOS (ignoring figures) to determine what is visible to you.

But now our newcomer rule is along the lines of

When you open a door, you are automatically moved onto the square directly behind the door into the new room or passage behind.

This rule has the advantage that it clearly only applies to an "opening door" situation and not a looking through an already open door or looking into a new passage or any other situation where opening a door isn't involved.

This rule has a second advantage that having been moved onto the square behind the door, you are now in the room or passage, so our first encountered, paired set of rules, can be used, unchanged to explain why everything in the room beyond is placed (because you are now in that room), and if it is a passage behind the door that you are now in, then you are not in the same room then use LOS (ignoring figures) to determine what is visible to you.

This rule has a third advantage in that you don't need to do anything different when it comes to corners and junctions because they are not in the same room so "if not in the same room then use LOS (ignoring figures) to determine what is visible to you" still applies unchanged.

However there is a disadvantage to this rule, what if I move onto a square in front of a door with my last point of movement and then the rules say that I can choose to open the door, but I have no movement points left so how can I move into the square behind the door? Turns out the designers considered this situation, that applies only in the "opening a door" scenario so they included a clarification in the "opening a door" section that "opening doors does not count as a move".

Conclusion
Personally I consider the right hand path to be the simplest route through this dungeon because the left hand path results in us having three rules in play, our initial pair (if in the same room everything is visible to you, if not in the same room then use LOS - ignoring figures - to determine what is visible to you) and our newcomer (everything in a room or passage is visible and placed on the board, provided that you are on a square next to the room or passage), but there is no evidence that I can find that supports the presence of our newcomer rule in the rulebook that wouldn't already be covered by our initial pair of rules in combination with the "when you open a door, you are automatically moved onto the square directly behind the door" on the other hand I can find evidence that supports the presence of this rule, the ""opening doors does not count as a move" which without this rule being in place, the inclusion of that text makes no sense at all.

So...

If in the same room everything is visible to you, if not in the same room then use LOS (ignoring figures) to determine what is visible to you.
When you open a door, you are automatically moved onto the square directly behind the door into the new room or passage behind.
Opening doors does not count as a move

Is both official and complete, in my opinion.

[Onan]

Except they aren't, imagine a door placed in the bottom wall of the centre room, on the furthest square to the left. From the square in the passage outside the room you open the door. If you use (1) then a monster in the bottom right corner of the room would NOT be placed as there is no LOS, if you use (2) or (3) then it would be placed, so not consistent.

Here I was unclear what I meant by "consistent". They don't provide the same results when compared to each other, as shown in your example. But each rule creates consistent results in itself for revealing a corridor from a junction and by opening a door into it. This is not the case for my experimental rule mix of 2) for entering passages and 3) for entering doors.

And should you really get 1 movement square for free just because a block fell onto your square?

The block fell in another hero's turn, because he triggered the block that fell on my square. So I'm allowed to "dive out of the way" on his turn. I think it is something different. But yes, there is no problem with giving the hero an extra square. And if we assume that opening a door requires stepping through, then you can do it "for free", because it doesn't count as a move. But what an impractical rule for counting squares! When players want to keep moving after the room is placed, often they ask
- "How many squares did I have left?"
- "I think you started from here and you rolled a 12, so you have 3 squares left."
- "Right, no, wait, I opened this door on my way for free, so I have 4 squares left."
- "Oh yes, and the new door also doesn't count, so you have 5!"

If I introduce this rule, I should better be prepared for this awesome custom quest the next time I play as a hero:
Epic Door Slide

I think there is a discrepancy beween the "Opening Doors" and "Setting up a Quest" rules that everybody has to resolve by deciding which one he likes more. If you deny the discrepancy and say "opening doors" has "moving through" RAW, you get the "free movement square" complications for no gain, and you will have to explain why you are supposed to place your character on the other side, although the rule does not explicitely tell you to do so. We have a good rule here where placement is very evident and "No backtracking" makes sense, but declaring it RAW goes too far I think.

Imagine that we are adventurers, negotiating the most perilous and challenging dungeon of all, the rulebook!

I'm afraid this dungeon uses the "Castle of Mystery" design and all who dare dive into it end up among the "host of monsters who were trapped in time". Let's hope we roll a or some day

I don't see a problem with your left hand path. If we leave targeting aside for a moment, there is no use case for a rule that handles visibility into a revealed area from an adjacent square. In a passage visibility is important for searching, but searching requires you to be inside the searched area, not adjacent. So why would the Dwarf even care about what he can see in the Barbarian's room?

The right hand path is also fine.

[Kurgan]

Now if enough people fall into the same pit... you can say the "floor gives way" (yet again) and everyone ends up in the "Caverns" board, where you have one last final fight/treasure hunt before the victor returns to the surface...


"How did you get back up here?"

"Wasn't easy!"

[Daedalus]

Figures blocking LOS (Daedalus)

Thank you for that explanation I now understand your "inscribed diamond" but whilst I think you are technically and geometrically correct, for me it feels more complex and harder to explain than assuming everything fills the whole square and you use the corner point of occupied squares (or wall corners including blocked squares), rather than the mid-point, as the pivot point for a geometric mirroring of potential targets.

We already have the concept of a figure occupying a square fully, from the movement rules, blocked squares fully occupy a square (for both movement and visibility), walls align to the edges of squares, and even you agree that if you choose certain furniture types to block LOS (and all types to block movement) then all of those "block the full square" so for me personally I think I'd adopt the same for figures, in the interests of simplicity and consistency.

That said I'm still thinking!

I hope that my second explanation that pivoted away from an "inscribed diamond" that focused on a circular area based on the diagram made better sense. Anyway, thanks for the acknowledgement. I can appreciate that you prefer to rely on the corner as the pivot point for ease of explanation. After all, the LoS of the diagram shows it.

Traps, pits, and certain spell effects also add to the list of things that fully occupy a square--all the more reason to stick with your choice. However, I'd discount all figures but the Ogre as fully occupying a square; it is the only one specifically noted to not allow friendly figures to pass through. For me, allowing a friendly to pass means that a figure is only partially blocking its square.

My choice on how to rule this rather dramatically changes LoS avenues, specifically opening diagonals. As a result, fights in rooms will work out a bit closer to the "any figure in a room is visible" rule of the EU rules. For me, bounded by the NA rules of LoS, this compromise is probably a good way to go (or at least try). EU players would have less reason to bother.

[Bareheaded Warrior]

I agree both paths or options are viable, my reasoning for choosing the "right hand path" for my clarification document is because it feels a better "fit" in terms of the rules as written (although I'm not claiming that either option is exactly and clearly what is written in the rulebook, if it was then we wouldn't need this discussion!).

What I mean by a better "fit" is if you go with the "left hand path" then ...

1) You need to create a new rule that isn't included anywhere in the existing wording

Everything in a room or passage is visible and placed on the board, provided that you are on a square next to the room or passage

Arguably this can be considered an interpretation of the "Opening Doors" rule but applying it to situations like passage corners where there is no door at all, feel like a bit of a stretch (not in terms of it being viable I mean in terms of claiming it as a better fit to the wording of the original rulebook).

2) It leaves you with a piece of wording that IS in the original published document (both 1st and 2nd editions) that remains unused and unexplained

Opening doors does not count as a move

Rather like when you put a kit together and it looks like the design on the front of the box and it works like it is supposed to...but you have a component left over and the niggling doubt that you didn't assemble it exactly as per the designers original instructions/intentions

I don't consider either of these reason to not use the "left hand path" when playing, but I do consider them reasons to favour the "right hand path" as the better fit for the wording of the original rules.

So in summary, what I'll be adding to the clarification document...

1st edition

Visibility

Models in the same room as the character are always visible

Models in passages or in different rooms are only visible if you can trace an unobstructed straight line from the character to the target. If the line passes through another model, through a wall, or through a closed door, then the target model is not visible.

Include notorious diagram

Additional clarification text derived from the diagram

The straight line must be traced from the centre of the character’s square to the centre of the target square (all, but specifically Elf to “Right Hand Side, Top as blocked)

A model blocks visibility only if the straight line passes through the centre of the square that it occupies. (Elf to “Right Hand Side, Bottom” Orc as blocked, Elf to “Right Hand Side, Middle” Orc as clear)

If the line touches a wall corner or edge but does not pass through the wall itself then the target model is visible. (Elf to “Left Hand Side, Top” Orc as clear, Elf to “Centre” Orc as clear, Elf to “Right Hand Side, Top as blocked)

Opening Doors

Characters and monsters can only enter and leave rooms through open doors.

Monsters cannot open doors

You can open a door by moving onto the square in front of it. You do not have to open a door if you do not want to. Opening a door automatically moves your model onto the square on the other side of the door, but this does not count as a move.

Having opened a door you can keep moving, if you have any spaces left to move.

As soon as a door is opened, the evil wizard player must place any pieces shown for that room, or visible in the passage on the map in the Quest book (apart from traps and secret doors). Once opened, a door remains open for the rest of the game, The evil wizard player should remove the closed-door piece and replace it with an open-door piece.

Note that, because you may not move through the same square twice in one move, if you move through a door, you may not pass through it again until your next turn.

Outstanding Issues

(1) Inconsistency between handling of targeting between models in the same room and model in passages or different rooms, even between small two square wide rooms "cells" and same passage even two square wide passages

(2) Double corner issue - if the line touches the left hand side corner or edge of a wall AND the right hand side corner or edge of a wall is it still visible.

(3) Figures block visibility (placement) of other figures and pieces directly behind them which including figures, furniture, blocked square markers, door pieces

2nd edition

[Both for placement and targeting] Models in the same room as the character are always visible

[For placement] Models in passages or in different rooms are only visible if you can trace an unobstructed straight line from the character to the target. If the line passes through a wall, or through a closed door, then the target model is not visible. (for placement)

[For targeting] Models in passages or in different rooms are only visible if you can trace an unobstructed straight line from the character to the target. If the line passes through another model, through a wall, or through a closed door, then the target model is not visible.

Additional clarification text derived from the diagram

The straight line must be traced from the centre of the character’s square to the centre of the target square (all, but specifically Elf to “Right Hand Side, Top as blocked)

A model blocks visibility for targeting only if the straight line passes through the centre of the square that it occupies. (Elf to “Right Hand Side, Bottom” Orc as blocked, Elf to “Right Hand Side, Middle” Orc as clear)

If the line touches a wall corner or edge but does not pass through the wall itself then the target model is visible. (Elf to “Left Hand Side, Top” Orc as clear, Elf to “Centre” Orc as clear, Elf to “Right Hand Side, Top as blocked)

Opening Doors

Characters and monsters can only enter and leave rooms through open doors.

Monsters cannot open doors

You can open a door by moving onto the square in front of it. You do not have to open a door if you do not want to. Opening a door automatically moves your model onto the square on the other side of the door, but this does not count as a move.

Having opened a door you can keep moving, if you have any spaces left to move.

As soon as a door is opened, the evil wizard player must place any pieces shown for that room, or visible in the passage on the map in the Quest book (apart from traps and secret doors). Once opened, a door remains open for the rest of the game, The evil wizard player should remove the closed-door piece and replace it with an open-door piece.

Note that, because you may not move through the same square twice in one move, if you move through a door, you may not pass through it again until your next turn.

Outstanding Issues

(1) Inconsistency between handling of targeting between models in the same room and model in passages or different rooms, even between small two square wide rooms "cells" and same passage even two square wide passages

(2) Double corner issue - if the line touches the left hand side corner or edge of a wall AND the right hand side corner or edge of a wall is it still visible.

(3) Figures block visibility of other figures and pieces directly behind them which including figures, furniture, blocked square markers, door pieces

EDIT: Figures Blocking LOS (Daedalus)

I hope that my second explanation that pivoted away from an "inscribed diamond" that focused on a circular area based on the diagram made better sense. Anyway, thanks for the acknowledgement. I can appreciate that you prefer to rely on the corner as the pivot point for ease of explanation. After all, the LoS of the diagram shows it.

Traps, pits, and certain spell effects also add to the list of things that fully occupy a square--all the more reason to stick with your choice. However, I'd discount all figures but the Ogre as fully occupying a square; it is the only one specifically noted to not allow friendly figures to pass through. For me, allowing a friendly to pass means that a figure is only partially blocking its square.

My choice on how to rule this rather dramatically changes LoS avenues, specifically opening diagonals. As a result, fights in rooms will work out a bit closer to the "any figure in a room is visible" rule of the EU rules. For me, bounded by the NA rules of LoS, this compromise is probably a good way to go (or at least try). EU players would have less reason to bother.

Sorry Daedalus I missed your post, but I think I inadvertently answered it already in this post with this piece

A model blocks visibility only if the straight line passes through the centre of the square that it occupies.
As "evidenced" by the Elf to “Right Hand Side, Bottom” Orc as blocked, Elf to “Right Hand Side, Middle” Orc as clear in the diagram.

This is my (current!) official approach, and whilst it is different from yours, I think that both approaches have a similar effect in that they retain the concept of LOS being blocked by figures for the purposes of missile attacks, whilst opening up the board more by limiting the number of scenarios in which the LOS is blocked.

I think my approach achieves this in a simpler way, effectively a figure only blocks LOS if it is between you and the target and is on the same horizontal, vertical or diagonal line, (like the queen in chess), otherwise it does not.

Ogres are something of a special case and I would be open to consider those, like tall furniture, as having a full square blocking effect, possibly in terms of movement (official rule), LOS (missile attacks) - a logical extension of the movement rule, and blocking Veil of Mist and similar magic effects (again a logical extension of the movement rule) but might draw the line at them blocking LOS (in terms of placement)...but this is probably a complication for the AtOH sections...

[BlackJax]

That was an epic journey, a perilous quest of 16 pages and certainly some nasty monsters to slay!

I don't remember this topic being such a tricky area back when I was playing HQ in 1999-2001 but then again we might not have been playing the rules right and my memory isn't what it used to be, so as this is a core part of the rules I wanted to make sure I understood it correctly before I start playing again.

One reason for some of the confusion I think is that different versions of the game have different rules so some people seem to be cross-threaded in that they are arguing from different versions of the game and never the twain shall meet. So to make it clear from the start I'm concerning myself with the original UK edition of the game 1989, the official rules as written rather than house rules, at this stage at least, and with a preference of the slightly later amended version of rules (can't remember the date on the rulebook but can dig them out if required) which I think is what is being referred to in this forum as the "second edition", with reference to the earlier "first edition" where clarity might be required.

It seems clear to me looking at the rulebook that there are two slightly different rulesets in the book, the first covering what a hero can see for the purposes of putting stuff out on the board and the second covering what a character can shoot out with missile weapons and certain spells. The first of these appears the simpler version, as it ignores figures, so I'll try and get my head around that first, before moving onto the second ruleset in a separate post.

What can be seen?
Deciding what can be seen by a player character is very important in determining what should be placed onto the board. Miniatures in the same room are always visible. Miniatures in passages or in different rooms are only visible if you can trace an unobstructed straight line between the two miniatures. If the line passes through a wall or a closed door then the miniature is not visible.

This phrase contains some key pieces of information

1. You should only place things on the board if they can be seen by a hero (I'm avoiding the awkward term "player character")
2. A hero can only see something if you can trace an unobstructed straight line between the two miniatures, that doesn't pass through a wall or closed door.

The phrase also includes another piece of information "Miniatures in the same room are always visible" which I don't consider as a key piece of information because it is redundant, if you look top down at the board you can clearly see that a figure placed on any square in a room can trace an unobstructed straight line to any other square in the same room that doesn't pass through a wall or closed door. I assume that the designers included this part as a rule of thumb to speed up play as they are telling you that you don't have to work out the "unobstructed straight line between the two miniatures, that doesn't pass through a wall or closed door" part if both figures are in the same room as that will always be the case.

This seems fairly straight-forward and is a common implementation in similar grid based games, the only possible points of contention that I can see are:

a) Infinite Lines: An infinite number of straight lines can be drawn between two squares on a grid, so to make this rule useable more information needs to be supplied, my assumption here is that the designers were referring to the straight line between the centre of the two squares in question as that is the standard for this type of game played on a grid based board

b) Touching Lines: Another possible point of contention is where the straight line touches on but does not pass through a closed door or wall, according to the rules as written the square would be visible (as it doesn't pass through or cross the wall) and I think this is correct, because most board games of this nature apply some form of the 50% rule in that if at least half of the square is visible then the square is visible.

c) Opposing Corners: This one is a little more complex and is a special case of the previous point. Where the straight line touches on, but does not pass through a closed door or wall, but it touches two different corners which are opposing. In this instance the rules as written suggest the square is visible, but many other games that use a similar system would rule that the square is NOT visible due to the 50% rule, one corner blocking visibility of one half of the square, the opposing corner blocking visibility of the other half of the square therefore the square is NOT visible. This may be considered a valid scenario to apply a house rule, but to be honest it happens in such rare scenarios that I wouldn't consider it a significant flaw in the rules as written.

d) Blocked Squares: Introducing the blocked square tile opens up additional complexity to the "unobstructed straight line between the two squares, that doesn't pass through a wall or closed door" principle because whilst a blocked square isn't a wall or closed door (the rulebook includes a definition of a wall and the blocked square tile doesn't match that definition), it is also clear that the blocked square is intended to block visibility in that you wouldn't lay out the contents of a passage that lies the other side of a blocked square tile than the heroes (or a double blocked square tile where the passage is double width). The logical way through this for me is to assume that the blocked square tile is effectively, from the point of view of the rules, a square surrounded by walls filled with solid rock, as both walls and solid rock are concepts that already exist in the game rules.

A note on furniture: I don't see anything within the rulebook that suggests that furniture blocks visibility, however the relative height of the figures in relation to certain taller pieces of furniture such as the cupboard and bookcases (and possibly the fireplace) suggests that it might. Looking through the Quest Books demonstrates a convention that these taller furniture pieces are always placed against walls, so again this may be considered a valid scenario to apply a house rule, but to be honest a taller furniture piece placed against a wall could only possibly block visibility in such rare scenarios that I wouldn't consider it a significant flaw in the rules as written.

[The Admiral]

I don t know, or care, what the official rule says, but for me, to fire at something you need a clear line of sight, but a Hero is aware of the presence of any monster in the same room or corridor as them even without los, and so they wouldn't lose the effects of anything that goes once they can't see a monster. It makes sense to me and that is wht guides most of my HQ.

[BlackJax]

Well my question was around the official UK 1989 edition rules as I want to understand the official rules before I decide if, what and why I want to house rule but I hadn't got as far as the "targeting things with missile attacks" bit yet but seeing as you've mentioned it I'll take that as a prompt to cover that now.

What can you target with a missile attack?

Spells can be cast at monsters or characters provided they are visible to the spellcaster. Miniatures in the same room are always visible. Miniatures in passages or in different rooms are only visible if you can trace an unobstructed straight line between the two miniatures. If the line passes through a wall or a closed door or another miniature then the miniature is not visible.

Another reason for some of the confusion is that the original rule around what can be seen, the "miniatures are only visible if you can trace an unobstructed straight line between the two miniatures. If the line passes through a wall or a closed door then the miniature is not visible" is generally referred to as the line of sight (LOS) rule. In some tabletop battle games, to avoid confusion, where the rules for line of sight and for weapons that use line of sight for firing are different then different terms are used "line of sight (LOS)" for seeing and "line of fire (LOF)" for firing weapons along the line of sight. In HQ the term LOS is used for both, so you end up with a description of LOS in an earlier section of the rulebook that is NOT blocked by intervening figures, and then later in the same rulebook a diagram that spells out an example of line of sight being blocked by an intervening figure, which appear to directly contradict each other. The important thing to note here is that the diagram stating "LOS blocked" in included within the section of the rules concerning missile fire and spells and is referring to LOS is the context of firing weapons along the line of sight and NOT in the context of seeing.

Assuming that is the case this piece gives us a couple more key pieces of information

3. To target a figure with a missile attack it must be visible (as defined by the earlier what can be seen ruleset)
4. If the traced line passes through another figure then the shot is blocked

Finally from the diagram provided in the rulebook there is another key piece of information which isn't mentioned in the text, that can be used to expand the last piece of information (4) above

4. (Expanded) If the traced line passes through the centre of a square occupied by another figure then the shot is blocked (this use of the centre also seems to confirm the same use in the earlier rule #2)

The Admiral, I think all of the above put together looks like your version of the ruleset is the same as the official version, although your use of the term line of sight, did confuse me for a moment. An intervening figure blocks your shot, but doesn't block your line of sight, it may well partially obscure it, but you can still see it, you just can't get a clear shot, so your shot is blocked, but I think that is just a difference in terminology.

So in answer to the OP's question "see" IS the same thing as "line of sight" BUT "line of fire" is different from "line of sight" in that it is blocked by intervening figures which line of sight is not.

Line-of-Sight One Pager.pdf

UPDATE: I've updated the one pager to reflect the KK situation, to add the large monster rule and to remove the "rule of thumb" as it is just confusing!

[Onan]

All this LoS is a very complicated topic, with lots of corner case situations. I don't think the designers had this in mind when writing the rules. The 9 year old target audience needed simple rules. On this forum I found the great hint that 2 prototype cards can be read when stopping the TV commercial video. The Fire of Wrath spell was meant to be played against doors and furniture, and the card also states the allowed targets:

This spell may be cast on any object or door in the same Room or Passage. The object and anything in it will then be destroyed. The spell may not be cast on Monsters or Players.

My guess is that this was the original spell targeting rule: "in the same Room or Passage", and that it was written on each card, much like the "The spell is then discarded" rule is now written on each card. This is a simple rule that doesn't even require the concept of visibility, but it has 2 issues:

1) In the 1st Edition rules they dropped the concept of "same Room or Passage" and replaced it by "same room or visible in a passage". I think this happened because someone detected a glitch in the "same passage" idea: If there is a blocked square in a passage, it counts as a wall and the content behind should neither be revealed when entering nor be a valid spell target.

2) It forbids spell casting through open doors, and I guess most players would instinctively assume that you would be allowed to do so.

I think the final wording addresses these 2 issues:

Models in the same room as the spell-caster are always visible. Models in passages or in different rooms are only visible if you can trace an unobstructed straight line from the spell-caster to the target.

So issue 1 is solved by dropping the "same passage" concept for spells, and only keeping the unproblematic "same room" rule. Issue 2 is solved by using a geometric criterion (straight line).

And here is my next guess: I think with "straigh line" they meant "horizontal or vertical". This solves the problem for most cases. The passages are all horizontal or vertical, so finding the first one in the path is easy. You also get a "tunnel view" into other rooms.

And then someone gave a hint that in the 2-square passages you would have to side-step to align horizontally or vertically with the target, which seems odd. And then he drew that infamous diagram that fixes all the problems

[The Admiral]

For me:
Line of sight is can I fire/cast at it. I trace a straight line between the centre of the firing square to the centre of the target square. It is blocked by any square that contains a block, which is a figure, closed door, wall or tall furniture. Some figures don't block such as a rat.

Seeing is what is placed in a room or corridor when opening a door or entering a new corridor. Everything is placed even if you don't actually have a los to it all. Obviously traps and secret doors are not placed.

A figure is assumed to be able to see everything in their los and everything in the same room or corridor as them even if they don't have an actual los to everything.

I hope this defines for you my difference between los and see. I don't know if that fits any version of the rules from 1989 to 2021, but it's how I play because it makes sense to me and I find it easy to implement.