I briefly speedran the game "Maximum Action", because I really like FPS games, especially old school fps. It's an extremely fun game for a casual playthrough, but man is it a messy speedrun. Everything in the game is physics based, including your own movement, so it's incredibly easy to get stuck or get unlucky and have your momentum be totally rekd.
It might be okay for an any%, but I made the horrible mistake of trying to 100% run it because it's a short game. Good god. There's no kill confirmed indicator, and because the enemies are also physics based they can trick you into thinking they are dead. They might get knocked over and lay on the ground for a few seconds, but don't let that fool you, they aren't dead yet.
I put many attempts into getting a legitimate run of the game, but probably like 95% of them were failed just because I would miss something and invalidate my 100% run. I ended up eventually getting a legitimate run, but I never submitted it to this site because it felt so terrible that I didn't want anyone to see it lol.
Here's the awful run that I never submitted, it shames me to this day:
I never made any attempt to improve it because the game just felt too clunky, I might try and get an any% run once the game releases from early access, but even that will probably be a nightmare.