A chess board trap is one of my favourite puzzles for a role-playing game.
Players enter a rectangular room with an 8 x 8 square pattern in the middle which touches each edge of the room (but as it’s rectangular players can move around easily before touching the squared).
On one of the spaces towards the middle is a pile of ash with what looks like old bones sticking out of it. On the left hand side one space in from where you are is an unmoving stone statue of a warrior.
A board is placed in front of the 8 x 8 square pattern (don’t refer to it as a chess board to the players) that has the following poem written on it:
Religious folk need cross me not
Or lightning will strike
Those who act like they’re made of stone
Will indeed be made of stone
If royalty should dare to tread
On any of my squares
Then they will be doubly dead,
In what manner, who cares!
If you’re a pawn
You may cross in peace
But start in your proper spot
Or you will have to cease
But warriors may stride across
Right to the other side
Then stone will move, ash be reborn
For an hour all abide.
P.S. I hate flies
The poem describes the different playing pieces in a chess game.
If players start on any space, then move diagonally (like a bishop in chess or ‘religious folk’) lightning strikes them doing 3d10 damage (or enough to take roughly 50% of a players hit points), particularly if there’s a large role-playing group).
If players start on the first square then move in a straight line (like a castle), they must roll a d20 and on an 8 or higher, they will be turned to stone.
If players start in either of the middle 2 spaces and move in any direction, they will be both be hit by lightning and must save or be turned to stone (i.e. like a king or queen, or ‘royalty’).
If players jump over the first space and land on the second space, then they can walk straight across unharmed (as a pawn moves).
If players carefully jump across the board as a knight moves in L shapes and jump all the way to the other side then anyone turned to stone (including the stone knight on the board) becomes flesh again and anyone turned to ash or struck by lightning recovers all damage (including the pile of ash on the board who becomes a wizard). Everyone can also walk over the board as they wish for an hour. The knight and wizard have been there for years and will aid the adventurers in their game. (Perhaps revealing a peace of history that helps solves a wider mystery in the game).
In the event that ALL the players are either turned to stone or ash, then they wake weeks or years later when another party frees them.
If players get really stuck with this (particularly if they don’t figure out that it’s a chess game) then have a troop of ghostly chess pieces appear and start playing a game of chess in front of them.