This was something I started wondering about when I was reading a thread about Star Citizen, and about how space combat flight games were much less-common than they had been at one point, how fans of the genre were hungry for new entrants.

Looking at this list:

https://en.wikipedia.org/wiki/List_of_space_flight_simulation_games#Space_combat_games

...there really were far more games in the genre being released in the late 1990s and early 2000s than there have been recently.

A similar sort of phenomenon occurred for World War II first-person shooters.

https://en.wikipedia.org/wiki/List_of_World_War_II_video_games

Back around the same time period, there was a glut of games in the genre, and they really have fallen off quite a bit.

Whether it's a genre like these two, that hasn't seen many new entrants recently, or a genre that just never grew as much as you'd like, what genre would you like to see more of?