WASD and Q to control the gunner. Arrow keys and space to control the assassin. The assassin has to touch the gunner to win. The assassin can teleport. The gunner has to shoot the assassin to win. You might want to use two keyboards because one won't be able to process enough inputs at a time for both players to move properly.
An old 2 player game I made a long time ago. I might make a newer version sometime. #old definitely a very helpful tag