I saw that all the categories for this game are either for PS1, PS2 or N64. The version I own is the PC version. Is it possible to play this version for speedruns or do I need to run the Playstation or Nintendo 64 version?

Leaderboard's a bit jumbled right now. There is a place for PC runs under the level leaderboard, for some reason.

I'm currently working with the site and the MK community to get these boards fixed up for you. We'll see what happens.