Cairo Corridor is a two player game where players alternate playing pentagonal tiles until a "corridor" is established. A corridor is a group of empty pentagons adjacent to each other that connects all 4 sides of the board. You may never place a tile that blocks the last possible "gap" for such a corridor. The game ends when there is only one possible corridor left an no more tiles can be placed adjacent to it. The winner is the player with the most tiles next to the corridor. In case of tie, the last player to play loses the game.

On BGA: In this implementation, yellow pentagons are how illegal moves are denoted. If you think about the rules a little bit, you will come to understand that these illegal pentagons will eventually form the final corridor. Pentagons with blue borders are scoring pentagons because they are next to illegal moves (which are the final corridor).