Have You Played? is an endless stream of game recommendations. One a day, every day of the year, perhaps for all time.
Six bullets in the cylinder of a snubnosed revolver is a good limitation to build a roguelikelike around. That’s Heavy Bullets [official site], an FPS kicking you into a procedurally-generated indoor jungle with only six bullets. You can collect and reuse your bullets, but that’s not much use when they’re spent on the other side of the room and a chirping mutadog is charging towards you.