Crossfire is a 4-player game where you try to shoot your opponent across the board.
Each player is positioned on a side of the board, and they shoot across toward the other side.
If shots collide, they cancel each other out -- this includes shots that collide at right angles (crossfire).
To fire a shot, click on one of your 8 slots below the board; or use the keyboard keys 1-8 (or asdf jkl;) to fire from the corresponding slot.