Slay the Spire, Cataclysm: Dark Days Ahead, TF2, Wolfenstein Enemy Territory, Morrowind to name five going backwards in time a little. I've been playing computer games since text adventures were the mainstay though( got my TRS 80 model 1 in the late 70's) so there are a ton I have to leave out. The NES was probably the greatest thing to ever happen to me as a kid though and all the games that you'd expect are up there on my list. Having a Super Mario Bros. at home that was almost exactly like the arcade machine was a freaking REVELATION. Soothed the wounds of PacMan on Atari/Colecovision that had been open for a long time.
Tough one, but if I based it on what game I've replayed from start to finish the most times, Symphony of the Night. This is significant because I rarely replay entire games.
Changes from time to time. Overall the best game I've ever played would probably be DayZ but the game I've put the highest amount of hours into would be either Runescape or GTA San Andreas Multiplayer (SA-MP)
I'm split between RimWorld and Dwarf Fortress. They are so close, and between the two of them lies the perfect game (for me). DF does a little more in some areas than RimWorld, and RimWorld does a little more in other areas than DF.
Like RimWorld is more moddable, but Dwarf Fortress has an actually 3D world and better terrain generation and background simulation.