Holy nostalgia bomb. This reminds me of wasting so many hours on Postopia as a kid.

Chex Quest HD is available for free on Steam

As a reminder, Chex Quest was just a total conversion mod of Doom

This and the Captain Crunch creature game.

I remember when I played this as a little kid thinking, "well this is just a rip-off of Doom" and feeling all superior about my game preferences.