I'm surprised I hadn't heard of this one before! A few developers have been building Nazi Zombies: Portable, a Call of Duty: Zombies demake powered by various enhanced forks of the Quake engine.
"A few developers have been building Nazi Zombies: Portable, a Call of Duty: Zombies demake powered by various enhanced forks of the Quake engine."
I'll try it on my Orange pi zero 3 just for giggles.
-EDIT- I just did (straight from their site), and welp... 5 minutes to load a map, lots of stuttering yet performance was okay'ish ( ~25 frames per second). Not bad for a little board with only 1 GiB of ram and the power draw capped at 2W.