No matter how much remixing today's culture is and no matter how many people have made at least one form of fan work whether it be fan art, fan fiction, fan characters, fan films, fan games or anything fan-noun, there has always been the issue that none of that is actually legal due to the fact that fair use doesn't explicitly protect a fan's good intention to contribute to the creation of their favorite franchise.
There have been many lawsuits against fan workers, especially from Nintendo. In the last few years, Nintendo has shut down hundreds of fan games of the Super Mario franchise and many others. Super Mario Bros X the fan game got shut down as well as Super Mario Bros Z the animated crossover Flash movie. The only game I know surviving so far is Mario Forever.
However, there are companies that use their fans as resources to make good games for them for real money. The perfect example of that is Sega when they allowed fans to create their own hacks of the original Sonic the Hedgehog games as well as their own engines, original games and even games that are original offsprings such as Freedom Planet and Spark the Electric Jester. Sega allowed the hosting of many game jams and hackathons for game developers to learn how to make games by remixing the original Sonic games and trying to make something awesome out of them. There have been fan game collections such as Sonic Megamix and very popular Sonic fan games like Sonic Robo Blast. Sega has never had any problems with fan games or any kind of fan work and they have always allowed their fans to use their intellectual property for their own enjoyment.
The question now is, is there a list, an article, an analysis or a method of analysis such as Freedom to Operate, in order to find out which companies are okay with the remixing of their intellectual property. Another question is if there are any open source video games that allow fan work to be done and under which license types (copyleft (GPL), copycenter (MIT)). Has anyone ever tried to figure that out? Please let me know as well as many other people who are too poor to hire a lawyer to tell them what's legal so that they can peacefully make their own fan works.