I have not kept up with gaming much for the past decade, so my list is going to be very dated. In no particular order:
- Starsiege: Tribes (Tribes 2 gets an honorable mention)
- EarthSiege 2
- EverQuest (very begrudgingly, but it did kick the era of MMORPGs into overdrive, and I was addicted to it for almost a decade)
- Star Wars: Knights of the Old Republic
- Mass Effect Legendary Edition (I'm counting the trilogy as a single game)
- X-Wing Vs. Tie Fighter
- Open Transport Tycoon Deluxe
- Cities: Skylines
- Star Trek Online (only because of storylines)
- Battlefield 1942
No console games on my list, because PCMR! :P
[Edit] Almost forgot Star Control 2!