Hello, I am looking for a game that I could potentially speedrun on a slowish PC. I would prefer it to be under 2:30 hours, and free (But I might pay if I had to-maximum $10-). I can practice it a lot so tough games are an option too.

You Have to Win the Game, Super Skeleman, and Cave Story are all freeware platformers that shouldn't be much of a problem to run. The former are short games, the latter is approximately an hour for a good run.