You are trapped in a room with a monster. As if that were not bad enough, there are shooters outside the room shoot at you when the portals open. To move forward, you have to shoot the bandits when the portals open. You can shoot at the monster, but it will only be stunned, and if you stay in the same room for too long, the monster becomes invulnerable to your weapons.
There are sixty-four versions of the game. Some militants shoot straight, others are aimed at, no matter where you are, others slowly, some quickly, others all the gates open at the same time and remain open, a variety of other portals open and close.