Hellgate 1993

A first-person shooter built to look like the year in its title: corridors, keycards, sealed sectors and secrets behind walls that do not announce themselves. Eight worlds, each of them two combat stages and then a boss, with health, armor, ammo and keys to keep track of and no regenerating anything. Hellgate 1993 understands what it is imitating well enough to get the pacing right, which almost none of the retro shooters in the feed do — the backtracking for a red key is part of it, not a chore bolted on.