Growing up with a clinical depression and an undiagnosed form of autism, games and books became one of my main ways to cope, and in some cases socialise.
I havent played alot on steam though, since ive always been mostly a console player if you dont count mmos, but heres my top 3 from steam:
Terraria: 594 hours. Me and one of my friends both got it back when it came out, and we had a habit of starting over every time a new content patch hit.
Skyrim: 224 hours. Ive probably got 3 or 4 times that since ive played alot on Xbox 360 back when it first came out. and ive even got it for PS4 aswell.
Just Cause 2: 174 hours. I love a big open world, and Ive got a completionist streak, and sometimes its nice to just do some busywork which is probably why i really like assassins creed games, although they wont show up since theyve all been played on consoles where its a bit harder to track.
But when we are talking about time spent in games there are 2 games that should be mentioned for me that wont figure on steam:
World of Warcraft: over 407 days played. WoW was largely how i socialised outside school/gymnasium in my late teens to early twenties. Sometimes just functioning as a chat program. I remember checking my playtime about a month before i quit the game at the end of the cataclysm expansion which is why the number isnt more precise.
And then last but not least:
Warframe: 2522 hours on PS4. Warframe for me has taken the spot MMOs used to have without as much of the social aspect since ive gotten better at getting that outside of games.
All in all alot of my life has been spent in games, and while i wish i had had the mental resources to use that time on something more constructive, most of us dont really get to choose how much energy we have for things or how much copeing is needed.