Conceptually, the game is simple:
- On each turn, make a chess move + play a card face down.
- Capture the enemy King to win.
- Only the King can be captured, and you can move in and out of check freely.
- If your opponent challenges the turn, reveal the played card.
- If the piece moved matches the card, your opponent skips their turn, else you undo your turn.
There are some extra rules:
- There's a different starting chessboard configuration - see the Rules Guide.
- You always have 4 cards in your hand - draw a card after each turn.
- Shuffle the deck at the start of your turn if you can't draw.
- Pawns are now "Guards" and move+capture 1 space forwards, backwards, left, or right.
- You can't move the most recent piece you successfully moved.
- If you would challenge a turn and lose, you may reveal Sheriff to cancel the challenge.
- If you move an opponent's piece and get challenged, you also have to reveal Trickster as the second-last played card to pass the challenge.
- After Black's 40th move, any check is a win (both Kings in check = keep playing). After Black's 50th move, the game is a draw.
(Basically) every rule of the game is written above. The Rules Guide and the One Page Summary are both trying to specify exactly what to do, so they are a bit more verbose.