I entered the Fretta Mod competition a few years back and worked on this mod called Decathlon. Basically a Track and Field style game. Well, I never commenced work on it, so I wanted to release the source code.
It contained working map entities that helped you build a track. The styles of games would be to force the player to be locked onto their lane, or for longer runs, to allow movement anywhere on the track, with out-of-bounds recognition.
Here is a video for your enlightenment: