Ranked mostly by my playtime therein. Thanks, Steam stats!
10: Hearthstone
9: Disco Elysium
8: Total War: Warhammer series
7: Star Traders: Frontiers
6: Hearts of Iron series
5: XCom 2
4: Kerbal Space Program
3: Final Fantasy XIV Online
2: Stellaris
1: Europa Universalis IV
If games out before 2010 were included, Lord of the Rings Online would rank highly (it’s become my default dork-around-aimlessly MMO just from the sheer amount of high-quality tourism and is more solo-oriented – at least for me – than FF14) as would Sword of the Stars 1, which was my go-to paint the space map my color game before Stellaris replaced it.