While it's still ridiculous and you'll have to fudge things (you can play with just one game system set + a bunch of mercenary proxies and a little imagination!) nevertheless there's some good news...
Mage of the Mirror remake will include SOME extra furniture:
2 "door bases" to insert cardboard into (intended for the "mirrors")
4 Portcullis doors
1 Iron entrance door
1 Wooden exit door
1 Tomb
1 Fireplace
1 Weapons Rack
1 Alchemist's Bench
2 Bookshelves
3 Treasure chests
1 Throne
(no extra torture rack, tables, cupboard or sorcerer's table).
Plus three extra double blocked square tiles (and even a new spiral staircase not that we needed one!).
Mage of the Mirror offers extra single block squares (6), pit traps (4), secret doors (4) ... (the EU edition saw no difference between blocked squares and fallen rock piles... you'll have plenty of skull tiles).
And Frozen Horror adds extra single block squares (6) (doubling as skulls as before).
It's all a big laugh, but if some people put their sets together to make some diabolical true 4 board setup with multiple zargon's and all the heroes taking their own path (in reality the board only changes over when all four heroes move over and the only way to get "lost" would be to use pass through rock spell to move to another section ahead of schedule)... that would be a sight to behold! 3d Printing the extra pieces would also be a cheaper way to do it.
When you play this for real, you clear the board once all surviving heroes cross over (they exit one at a time until all have exited, then you clear the board and start afresh). It's amazing to think how complex this adventure is and so it's no wonder that a few errors were made (duplicate furniture within the same section in a couple of cases) so no shame in imagining. The problem of one hero using pass through rock and wandering into the maze on his own, having to cross over through a different door could easily be resolved by Morcar/Zargon just placing him with the party again when the board "resets" to the new configuration. It's much easier viewing the color coded version to imagine how it all works (nothing against phoenix and his re-creation via the NA questbook conventions). There's also potentially no limit to the number of monsters IF the Heroes keep crossing back through the doors and refreshing the board to fight previously abandoned/killed monsters once again. There's no special reward for defeating them, but it could go on forever until the targeted bad guys are destroyed and the quest comes to an end...
