So i thinked about this game like a month ago. concept is simple: we have 2 players (Yellow, Red), red one can't go through red walls and gray walls, same for yellow but he can't go through yellow and gray.   

There are ghosts. They can kill all players.

There are turrets. They shoot players.

There are buttons. They can destroy walls, teleport objects.

Teleport. teleports players.

Closed walls.

Keys for them.

The goal of the game is flag with a color that matches player's color.

hope you like it ;)