What's a good game that never got mainstream popularity?

I've been looking for some new games to play recently, and I want to get some opinions on games that you feel have been overlooked and given the attention it deserves. Any games anyone?

I would say Founders Fortune. Very good game. Also Miscreated, it is a zombie apocalypse open world game. It has been played by some youtubers but didnt really reach mainstream popularity.

half life, i guess? like the original hl1, i mean it came out in 1998 so im not surprised its not mainstream but still deserves more credit