Looking for a game that I can run and improve a lot in, I'd rather not do the most popular because I wanna try and find some nice bugs

Syndicate (2012) is highly underrated. There's tons of skips to perform and a couple new ones found recently actually! Perhaps you can be the one to find more? Give it a look if it's the type of game you're interested in!

https://www.speedrun.com/syndicate2012

play a game you like playing. If you play some random game, you probably won't enjoy it as much. find a game you like and start learning it, if you don't like it anymore try somethin else

Boodunnit?! is a unknown 3D platformer with many different routes to find and has no glitches discovered at the moment. id always recommend it to new runners. it's on steam, itch, and gamejolt all for free!

https://www.speedrun.com/boodunnit/