Good god, so far no answers, I've done the same search and came empty handed. There's minecraft as an example of a not.so.good example though, because it's really limited to a low res.
The search is about a game where you can make textures for everyone else to see, games that have steam workshop or are modded offline doesn't count because of the online factor and you can virtually mod textures of any game.
For the next people that answers, at least read the tittle.