Why Do RPGs Fail

I was looking at the wide variety of RPGs on the store shelves recently and got to wondering what separates a Dungeons & Dragons from a Chivalry and Sorcery, a Pathfinder from a Lord of the Rings, a Shadowrun from a Cyberpunk? Why is one comparatively successful in the industry while the other, after some initial success goes out of print or languishes in relative obscurity. Chivalry &Sorcery, Lord of the Rings and Cyberpunk all had substantial success during their first release, but the relaunch of C&S soon fizzled, LOTR died as Decipher imploded and the release of an updated Cyberpunk may have done well in direct sales but hasn’t gotten any footprint in brick and mortar stores. Some thoughts on why to come.