Ah, the magic of config files. TheCircuitChaser wasn't able to run the beta for Call of Duty: Black Ops 3 very well on his PC because it's lacking the tweakable video settings that should be in the final game, so he decided to see how crappy he could make the game look. By digging into the game's config file, he was able to make the game turn into a low-res monstrosity that resembles a PS One game.
Is this becoming a thing with video games? Someone pulled a similar stunt with The Witcher 3, though Geralt's adventures more closely resembled the PlayStation 2 era.
If you'd like to make Black Ops 3 look awful, too, TheCircuitChaser dumped his settings here.