In your opinion, what's your favourite singleplayer FPS?

There aren't many of these around anymore. Looking for some recommendations as I really enjoy this (somewhat rare) form of game.

Im not sure if its a FPS game, but Subnautica definitely is a fun one. I love it.

Dying light is really good, Subnautica aswell. In general I like survival games.

Must Be Serious Sam. It was a good game before. But she is died.

Dishonored is one of my favorite! Nice story and ending