Others will be reminded of Doom, or even Wolfenstein 3D, and those aren’t bad comparisons either, but the mix of high-tech with organic is a visual reference to the classic AvP (and maybe to Doom, I never really played it, but definitely not to Wolf3D).
Understand that this is old school in other ways. The game lets you save progress, but only at the beginning of each level. For the hardcore, there is a mode where there are no checkpoints. There’s no minimap either, but there also isn’t regenerating health (the scourge of modern FPSs in many people’s minds), so you’re getting both the good and the bad of the old school. But all in all, it controls well (save for the lack of an ability to invert the Y-axis, though I have a Mad Catz controller with a physical Y-axis inversion toggle so it didn’t affect me any), and is very fun to play if you’re looking for an old school fix, and costs only $1 making it hard to pass up for fans of singleplayer FPS campaigns.
Here’s what the developer (CoderSystems) has to say about the game:
“Alien OverKILL. Clear the space ships of alien monsters in this first person 3D alien horror shooter.”