Transport Tycoon, using OpenTTD. If you’ve never played it you can download OpenTTD and use their graphics, sounds, and music replacement sets to play it for free. However as I own the base game I like to keep the original music as it helps to drive the nostalgia.
I love Doom, and I’ve been playing it since I first got hold of the shareware episode, but when I really need a comfort game it’s almost always Transport Tycoon.
Vampire Survivors, and Pico-8 games via Emudeck. Once I’m bored of those I plan to spend a bit more time with Snowrunner. I’ve never really got into it, but it looks like my sort of game.