specifications.md

Sokoban Game

Players

• Support multiple players.
• Each player exclusively takes one position and other players and boxes cannot be moved to that place.
• Players can only move one box at once.
• For simplicity, we support at most 2 players (This constraint should only be checked in InputEngine. Other parts of the game should support arbitrary number ([1,26]) of players.).

Actions

• Player 1 moves with W,A,S,D; player 2 moves with H,J,K,L.
• Player 1 undo moves with R; player 2 undo moves with U.
• A number can be given following actions to repeat the action for certain times.

Winning Condition

• All destination positions have been occupied with boxes.

Deadlock Condition

• None of the boxes in the map is movable.

Undo

• There is a limit on Undo actions, which is specified when game starts.
• Checkpoint every time a box is moved.
• Undo actions reverts the game state to the last checkpoint.

Text-based Representation

• @ represents box destinations.
• # represents walls.
• A-Z upper-case letters represent players.
  • Each letter represents a player.
  • There should not be duplicate letters in a map.
• a-z lower-case letter represents boxes that can be moved by players with corresponding upper-case letters.
  • E.g. boxes represented by a can only be moved by player A.
• . represents empty position where a player can move to or move boxes to.

Map Validation

• The map must be closed with walls.
• All players, boxes and destinations must be inside walls.
• For each box, there must be a corresponding player who can move this box.
• The number of boxes must be more than the number of destinations.
• There must not be more than one upper-case letter for each player.
• (Optional) The game must be winnable.