Games That Used to be My Little Pony Fangames
Online fan-bases for things usually make a whole ton of art, but never really any fan-games. There's two exceptions to this that I've seen: Touhou fans, and My Little Pony fans, both of which seemed to dominate part of the internet circa around a decade ago before seemingly receding quietly into their own corners.
But whereas Touhou has an insanely open license which, to hear it told, effectively gives fans full permission to make whatever, Hasbro loves sending C&D orders. The end result is that the few large-scale MLP fan-games to exist have lived on by removing as much in-game evidence to their origins as possible.
Note: There are a couple examples of games that not only still exist, but are fairly obviously tied to MLP, such as Pony Town and Legends of Equestria, however both games seemingly avoid any directly copyrighted material.