I was going to say replaying but I feel like that limits the question to games like Prey or Fallout New Vegas that have endings and games like The Sims 2 or Cities Skylines where you can play indefinitely end up excluded.
I’m not really referring to games like League of Legends where you’re coming back every month. More so games where you stop playing for an extended period of time.
Star Wars: The Old Republic. I don’t care about all the MMO stuff, but every time I watch or read something star-wars-related, I want to fire it up, get the one month subscription, and go on with some single-player story I need to finish. This happens twice a year more or less.