Comment by hombre_fatal

On the other hand, games are so hard to build and require so much vision that despite decades of gaming history, volunteers/hackers are mostly limited to modifying existing games rather than building a game from scratch.

You use Super Mario 64 as some sort of low/achievable bar for what volunteers might be able to build, as if SM64 is an easy game to build, yet nobody is building games like that on a volunteer basis.

Even look at the engineering that went into OpenMW: once again hackers were only able to recreate a game engine that runs existing game files (Morrowind) which is the easy part of building a game.