I've played World of Warcraft for the past 11 years, on the same warlock I was gifted long ago... Actually, I played a druid some beforehand... How long was I playing!?
Anyway, beyond that... Hmm... There's Star Wars Battlefront 1 & 2 classic versions. While I can't prove it on steam, back in the day I played them so much! No game of that kind nowadays compares to the space battles in two! Every now and then I go back, cuz I bought them on steam and replay.
And Shadow of Mordor, I play it off and on, but it turns 10 this year. While i've spent more concurrent time with it's sequel, Shadow of Mordor is somehow better in my eyes. I like watching the orcs build their legends up, and it's amazing really. Part two doesn't really let you do that too much without having to put your hand into it.