Demon of Something. No, not Angel. Demon.
Bored on assaulting all hells by yourself? Tired of being the hero to wipe out evil? Let's switch the roles!
You are now a puny imp, sent by yourself to assault a human stronghold. Your mission: break through the mortal defenses to destroy the latest innovation in their weapons technology, the dreaded Cyber-Titan! What waits you is humans, sergeants, captains, and commandoes, all with their Former prefix removed, as well as vicious bloodthirsty hounds to replace demons, small attack drones instead of lost souls, mobile heavy weapon turrets instead of cacodemons, power armored robot soldiers instead of hell knights or barons, and other deadly and scary machinery of mankind, the best they have to offer against the forces of hell! What is a tiny demon to do?
You have naught your fireball and pansy claw attack. Worse, while you could definitely scavenge some weapons from your fallen enemies, you have never seen such high-tech magic before, and must learn yourself to use them in the hard way: thus, any traits involving the use of any sort of weaponry (SoaG, Reloader, Triggerhappy, etc.) cannot be chosen at all until you have handled any weapon that benefits from them!
Also unlike Doomguy, if YOU don't survive, there are hordes of unlucky imps behind you, ready to be sent for another go immediately afterwards. Good luck!