I was very interested in speedrunning for a while but I couldn't find a game to speedrun myself. I played around a bit with both Donkey Kong 5 - The Journey of Over Time and Space (a pretty funny bootleg) and You Have to Win the Game (a free game on Steam) and I got pretty good but I just couldn't beat the people who really grinded out good times.

It was just recently that I started speedrunning for real. I was watching a stream on Twitch for a recently released game called Parallax and I was hooked as soon as a I spotted a bug in the game. I bought the game instantly and started playing around with that bug and I ended up getting that streamer hooked on speedrunning the game as well. Together we started getting pretty good times and we even got in contact with the developer, who decided to patch out the bug but add a checkbox for us so we could re-enable it.

I ended up not beating the game completely before I started running it but just as crush_overider said you should absolutely make sure you beat a game before you speedrun it, because the speedrun might end ruining your normal experience of the game.