Sanctuary 17 is inspired by the old Intellivision game Night Stalker, although it's bigger and has a sort of narrative attached.
It's a one-hit shooter in which you are confined to a maze with only a flashlight to light your way, meaning you can only see a few squares ahead. You can, of course, shoot, and can also 'shield' against enemy fire, but both actions consume energy, which is regained by picking up drops from enemies.
The farther you get before dying, the more 'followers' are added to your 'party' -- the equivalent of lives. However, when you die, the shield remains at the dead body, and you must go there to regain it, which is a bit of a pain as there's no automapping.
Most bots glow a bit in the distance, but there are also 'natural' enemies which are invisible until you're right atop them, and do not drop energy. A variety of weapons and such are available over time, and there are, apparently, three possible endings (other than losing, of course).
The game is interestingly tense not in a bullet-hell dodge-and-shoot way, but because you can't be certain of the layout beyond your immediate surroundings and a misjudgement or lapse in timing can cause instant death. It's a creepy little game, in other words, despite its 8-bit era graphics.