Simulators are one of the earliest PC game genres, and remain compelling experiences to this day, even if they're not as popular as they used to be.
I like all kinds of combat flight sims; the MS Combat Flight Simulator from 1998 was something special, and I've had some similar fun in IL-2 Sturmovik. The newest civil air sims are pretty great too, I'll pop on a podcast and make a flight. They're particularly cool in VR.
I've also found the MechWarrior games to be fun, but I've only played 2 and 5. I got to play a bit of Steel Battalion with the full crazy controller at a con a few years back, and that's got to be a lot of fun once you really know what you're doing.
So what's your favorite sim?
Derail Valley Simulator. I like my trains.
If you like building sets, you should check out Rolling Line.
Not so much the collecting. I like learning how to drive them, and driving them. I blew up my steam engines the first several times I touched the controls
I should get back into that one. I played some in early access, and it was fun.
Depending on how long ago it was, we've had a couple of updates recently. You can now paint all your engines, and there's a ton of gadgets