Sanctuary 17 sees you exploring a maze with only your torch and the occasional dim external light source to guide your way. Robots patrol the corridors and will shoot you on sight. Just one shot will kill you, so it's critical you keep an eye on their movements and sneak up behind them.
Energy is your key resource. Every shot you fire consumes power and once depleted you must wait for it to slowly regenerate. You can also replenish your energy meter by collecting cells from destroyed bots. But you can also spend it to power various computer terminals which not only save your progress but flesh out the story through email and other communication with lost colleagues.
It's wonderfully atmospheric as you uncover more of the mysterious world you're exploring while the lean gameplay evolves into a tense game of cat-and-mouse. Thoroughly recommended.
Sanctuary 17 [Twofold Secret]