I don't know about "never intended to be played" but I have designed whole systems around very particular concepts.

For example, what is the entire system was designed around random character generation? It wasn't just "oh well, its not like you get a character creation screen at birth" but setting was built around a bunch of people being thrown into a new world with new powers that they had very little control over. Plus making it so that who is "overpowered" gets pushed around a bit and things like that.

I also created a combat system that was designed to simulate the feel of action movie combat more than D&D's exchange of blows system. Never created the rest of the system so I'm not sure how well it succeeded on that.