I like Doom. I think it's a glorious mishmash mess of wildly conflicting goals and aesthetics, and it's also a vibrant mod scene the kind of which is kind of lost in current games that have a vested interest in code and asset obfuscation. Sometimes I even make things for it.
This was my first serious attempt at a single-player Doom map. In retrospect it is a little linear, but we all have to start somwhere.