In terms of absolute length in years? Minecraft. First played it in middle school when it was still in beta, a few months (or maybe a year?) before Nether even was a thing. Last played… maybe 1-2 years ago? If Luanti/Mineclone also counts then last month. Ironically I never liked Minecraft that much… only “gotten back” into it for like a week or two at a time

Second longest is probably Skyrim (honorary mention of The Binding of Issac, but rebirth is technically a new game so…), both of which I liked a lot. Played both quite a bit in high school, and still played a bit within the past year

My actual comfort game hasn’t even been developed until 7 years ago