I agree that the community decides on what is canon. However, I don't think anything can become canon. Fanfiction will always be splintered from canon until it gets adopted and published by the IP owners. So, "Goat Simulator" speedruns will always be performed on a version released by Coffee Stain Studios, or whoever owns the game in the future. You could rip up the source code, mod the game, whatever, and do speedruns. If it's popular then it's a new category, but it won't be a "Goat Simulator" speedrun, it will be a "Goat Simulator++" speedrun. What official version of the game the community decides to use for the "Goat Simulator" category can be contentious, as the developer could have a range of releases that change things significantly. Just look at half life 2. The most popular category is the release version of the game because you can fly around at mach 1.