I mostly played on consoles and my most played game ever with an absurd amount of hours would probably be Tekken 2/3, not 7000 hours of DOTA absurd but still, 2-3 hours almost every day for almost two years adds up. On PC I probably cracked 100 hours in Daggerfall/Morrowind, Fallout 1 might be up there, Master of Orion 2 and Jagged Alliance 2 of course, Baldur's Gate 2 is a long game especially if you suck at it. Then games became shorter, I remember getting through most of Max Payne 2 in one sitting when it released and it felt so short. Then I played it a couple of years ago and now it felt pretty long, 10-12 hours isn't that bad especially if it's played in 45 minute chunks every other day.
Steam stats:
Alan Wake - 22 hours (with the DLC's, also played it on 360. Not a fantastic game but the memory of the monotonous combat in the woods fades while the good stuff leaves an impression)
GTA 5 - 15 hours
Civ 5 - 12 hours (almost a full game!)
Tomb Raider - 11 hours
XCOM - 8 hours, I wasn't fond of it.
That's from a relatively new account from 2016, I recently recovered my old one(don't tie personal shit to company e-mail!) by eventually guessing the username and password, that one has a collection of games from before they tracked time spent in them.
Old account.
I actually had an even older one that I lost(don't tie personal shit to school e-mail!) from the early steam beta back when it was nothing more than server browser for Counter-Strike. Prior to the hat economy people were buying accounts with low UID's and I would have sold my account in a heartbeat if I was able to.
...yeah I think I have a good idea of what kind of talkative dementia patient I will be.