>>928181
Doom. Some time ago I had the idea to add custom skins and let the bots fight on a FFA match. I made a proof of concept some time ago, I modded the base doom guy skin to add a custom head and also imported some random characters and let them fight on Brit 10. Custom sound effects can be imported too (taunts, death sounds, etc.)
It ain't hard but it's tedious, specially if the character doesn't have complete 3D sprites (that is to say, the 8 different views allowed by Doom), the Connie model wasn't difficult because the sprite sheet already had the 8 points of view, but I imported the Zero model specifically to see if I can make a 2D model work on a 3D environment and it kinda worked for the most part. The main issue is that, unlike PES you can't import ripped models, you have to use sprite sheets (of course there are custom skins wads, but they are very few by comparison and most of them are custom Doom sprites or ripped from other FPS), so for more obscure boards with less userbase you would have to make the sprite sheet from scratch, I tried to circumvent that issue by editing only Doom guy's head but that was a pain in the ass to do and the result was kinda crap. In other words, smaller boards such as /fur/ and /monarchy/ would need to make their sprites from scratch.
It would be fun to set something like this, but I can only help with importing the files and setting up the matches, I can't help on designing the sprite sheets since I don't know anything about that.