For Your Consideration: The Fairies' Checkmate
This puzzle rests on two pillars.
The first is how to present dungeon obstacles in Dungeon World. When considering what to do to the PCs when there aren't monsters about, when "the dungeon" is the only thing to act, you need to consider what "the dungeon's" motivations are - or, rather, the particular mix of the original builder's motivations, its current occupants' motivations, and ways to express environmental threats as though they had agency.
Fortunately we already know what the Ghost Tower of Inverness is all about - the PCs are effectively running around inside a combination lock constructed by the Great Galap*, which he knew how to operate because he built it, and where he occasionally dumped the hapless for sport. But time is merciless and has ground some features of it down, creating hazards born from decay. So, something like:
*yes, I know that's not the whole of the original name but I'd rather not reproduce it
The Ghost Tower of Inverness
Impulse: Guard the secrets of the Great Galap
- Demonstrate the intellect of the Great Galap
- Yield to the power of the Great Galap
- Succumb, at last, to time
The second is that there are more chess pieces in heaven and earth than have been dreamt of in your philosophy. They're broadly called "fairy pieces", and they can do a whole lot of things. There are fairy pieces that move like knights but the L is larger, fairy pieces that take a bishop step and rook it from there, fairy pieces that make any number of consecutive identical knight moves, fairy pieces that capture at a distance, fairy pieces that have to hop to the opposite side of a piece to capture it.
Don't they sound like just the sorts of playing pieces you'd bring in to demonstrate the intellect of the Great Galap?
So if you're thinking along the theme of "human-scale chessboard", how is something like that going to yield to the power of the Great Galap? How would it open to him but not anybody else, while still being theoretically solvable by mere mortals so he can laugh at them for not doing it?
Well, one possible way is that it's reenacting the last few moves of a game of Wizards' Chess (featuring various fairy pieces) that he was particularly proud of. Galap would simply wizard the stone pieces from some sideboard out onto their starting squares and act it out in an appropriate way, but the PCs will have to step into various annotated starting squares and act like the pieces would.
In this way you can have a puzzle that offers opportunities to suit a class's abilities. Not directly suited, necessarily, but the elements of the puzzle make certain demands of the party that various PCs may be suited to step up to.
- What's going on here, what are these pieces? This is a question one of your lore-inclined characters can certainly answer.
- How do we solve this puzzle? This one's a bit wider. Galap's checkmate is probably not a matter of lasting record in the wider world, so straight lore is right out. But an investigative character may have earlier found a personal journal, lavished with protective spells among other rotting books, that recorded Galap's games, or at least the ones Galap won. An intelligent character may be able to work out how the checkmate progresses just from the setup of the board in front of them. A perceptive character may pick up hints about how it progresses based on the wear and tear of the play surface as Galap acted out the combination.
Both of these should fail heavily forward since they're blocking the adventure from continuing. When players skunk their rolls (yes, "when", the dice never cooperate) they're not clueless but have some painful experimentation in front of them to pick the right result from a couple of alternatives. Or they can get lucky!
As for the movements of the pieces themselves, here are some challenges that may appeal to various PCs:
- This piece makes long leaps. A PC has to cover a large distance on the board without touching down on it until they get to where the leaper would stop its movement.
- This piece makes a strikethrough capture. A PC can keep themselves planted on the board, but they have to topple a heavy human-scale stone statue, representing the capture, without notably breaking their stride.
- This piece makes a capture at range. Someone (not necessarily the related PCs) needs to topple a heavy human-scale stone statue once the PC is in position.
- This piece is the decoy that opens up the defenses. The PC's "piece" gets "captured" as part of the checkmate and the PC will need to leave their square and not touch the board until the puzzle is complete.
- Succumb, at last, to time. Remember that one? One of the squares that a PC needs to land on has fallen down as the earth shifted, or otherwise become inactive, and the PC will need to activate the square by mystic trickery or a 50-foot drop.
I hope this answer comes too late to be helpful for the original problem, because the alternative is the most legendary of scheduling conflicts. But as a special case of a general solution for adapting an earlier module for Dungeon World, take these points and go forward:
- take the history of the existing dungeon and query the motivations of the actors involved, to create "the location moves" to help you extemporize
- when your game world contains things from the real world, like chess, it can be beneficial to research their history; a story needs to be plausible to its audience, but history can contain all manner of implausible twists you can productively use to vary things from players' expectations
- when creating obstacles in the game, consider how they represent challenges to the PCs, not to the players