"Factor X" Factor Evil mode playthrough
Content warning for stupid amounts of blood and gore.
An indie game by Beau Langston, released under the Fallen Angel Industries banner in June 2001. Download it here: https://kliktopia.org/details/Factor X.html
Alternately referred to as "Resident X", one of two bonus modes that pay homage to a PlayStation classic, in this case Capcom's Resident Evil. It transplants a scaled-down facsimile of the Spencer Mansion into top-down format pretty well, borrowing a few of its plate-fitting and sheet music-playing puzzles, before seguing into romps through a graveyard and a laboratory.
You have limited visibility in this campaign, so I had to map it out ahead of time; it's shockingly easy to get turned around despite how small the mansion is! Zombies take five shots of the Glock to take down, and ammo is a rare commodity in the early portion, requiring you to kite them or lure them away to be able to navigate safely. There's no means of refilling your health to my knowledge (despite what appears to be a herb garden you pass through), so every hit counts!