Sadly and relatedly, the Descent series (6 degree of freedom FPS) was an intense test of skill unmatched anywhere else, and the last release in that series was ~13 years ago. I don't know of any other newer games in the genre.

Competitive FPS gaming reached a peak around 1998. Since then, the only games I've heard of with similar high-level competition have been in the RTS genre. "Watered down" seems to be the name of the game nowadays.