Edit: Going by what y'all have said and what I found, I would say they are at least set in the same (or loosely based) world even before someone uncovers any official statement about it.
I am by no means an expert and have never seen the game in the wild, much less actually played it myself! The only exposure to it I had as a kid was a tv commercial, but we already had Hero Quest, so I kind of forgot about it. It's meant for two players (or two teams). Wipe out the enemy, winner take all.
Battlemasters seems meant to be to tabletop fantasy wargamming, what Heroquest was to dungeon crawler board games. Maybe a more hardcore version of Risk too when you think about it...
The artwork on the box looks very "warhammer" -esque to me. Don't think there were ever any expansions, just what you get in the big box.
BM has a huge plastic battle mat you fold out covered in hexes... you put up towers and cannons, and little platforms that have units plugged in. You draw cards and roll dice to defeat the other army. I used to get this confused with a different game "Weapons & Warriors" (the one where you literally fire marbles out of spring-loaded cannons and rubber band balistas to knock over each other's figures).
How are they similar or connected? Made by the same people (and advertised as such "From the Makers of Hero Quest"). Milton Bradley & Gamesworkshop 1992 and targeted at the same demographic (age 10 to adult).
BM has the forces of the Empire fighting the forces of Chaos.
The solid color plastic Citadel miniatures are very similar. The scale and even the color choices are familiar (neither here nor there) although there are now yellow and black units in addition to the familiar dark green, red, dark red, blue, dark blue and gray (no undead, fimirs, elves or dwarves mentioned that I could see) with mainly gray architecture.
Now the figures slot into larger formation/company unit bases (green, black, beige, etc) rather than having individual bases (and stickers to apply to shields and labels to differentiate units), but many similarities exist...
The Imperial side has red soldiers (including crossbowmen and halberdiers) that look very much like the "Men-at-Arms" from Hero Quest (their outfits are identical other than the chest armor being covered with cloth instead of bare metal like in HQ), alongside armored knights. Other members of the Imperial Army strongly resemble the "men at arms" found in Advanced Hero Quest / Mighty Warriors.
The Chaos ("Chaos Army"/"Forces of Chaos") side has a dark blue (or black) "Ogre" that is like a retooled version of one of the Ogres in the ATOH (he's larger and has a different head and a bit of Fimir style belly armor). There are dark green Orcs, though they are wearing a bunch of armor so they look slightly different than the HQ orcs, but the faces look the same, ditto for the goblins. The Chaos forces also feature gray Chaos Warriors (their horned helmets lack the little "ball" between the horns characteristic of Hero Quest). The term "Doomguard" is used to refer to certain Chaos companies. There are also goblins in the same color plastic. The bad guys also have "chaos archers" that are mohawked humans.
Some of the greenskin bad guys ride giant wolves. There are also Beastmen, which were a figure rumored to be part of some of the unreleased quest packs.
I used to think BM was a NA exclusive, but there were European versions released (Dutch, German, French, Spanish) and also Japanese. No idea if there were rule variants, the components seem the same.
The minis are so similar, many fans have modified them for use in HQ... you can find pictures online.
A similar type of skull tile (painting of a skull on a black background, not identical to HQ) is used for damage counting. Terrain and other effects are simulated by cardboard tiles, mostly.
You get 6, six sided (square) plastic dice that are red with white markings, but feature skulls that are reminiscent of Hero Quest (the shields are totally different than either of the shield types on HQ dice).
Is it "Warhammer fantasy" or is it "Hero Quest" ? Or its own thing?
Is it supposed to be "canon" for HQ? I don't know, and it doesn't concern me either way, but its cool to imagine this is you playing out what's happening in the background during quest packs. I didn't see any actual maps of the world but cruise through the terms in the manual to see if you find any matches I guess.
In BM, the Imperial capital is called "Altdorf." There is a mention of a river called "Reik," and some place called "Grunburg" that had "fallen" to Gorefist, commander of the Chaos Hordes. Baron Delbourne (or Delborne) and Duke Blitzen (or Blitzein) are mentioned as leaders whose forces supplement your "Imperial Knights." Apparently the Chaos leader is invading the borderlands of the Empire, in some place called the "Reikwald" a heartland featuring plains. There are a series of five "battles" which progress the story of the invasion campaign. There is a river called Tengin. I didn't read the whole thing to see if there was a way to create your own scenarios or if that is it, the bad guys attacking, the good guys trying to eliminate the invaders before they violently overthrow the Empire.
Chaos companies include names like Grom and Uglub (Goblins); Blackfang and Bogrot (Wolf-riders); Doomguard and Fellmor (Chaos Archers); Gazkull and Zogrod (Orcs), Bale and Flint (Beastmen); Goreband and Finmar (Chaos Warriors); Gorefist (Champions of Chaos) and the Ogre Champion Grimorg.
Imperial companies include names like Melgar (Imperial Crossbowmen); Bogenhaffen and Grunburg (Imperial Archers); Reikwald, Altdorf and Grunburg (Men-At-Arms); and the aforementioned Delborne, Blitzein and Prince Normand with the Imperial Knights and Lord Knights of the Empire. And yes, there is a mighty cannon.
More info from
BoardgameGeek