Mass Effect Trilogy. Each game when I initially played had 3-4 careers of 50 hours. This was when one game’s choices affecting another game to this degree was very new so I would be trying many different permutations.

Definitely the case if we include LE later on.

Chose to live the DINK life, loving it.

Probably GTA Vice City back in the day. So much room to just dick around and kill random people.

Mario Kart.

I had over 10,000 hours of Call of Duty 2 (2005 version). 4000 hours of the first Call of Duty Modern warfare and currently have 3600 hours of Csgo. It’s common to run into 6-8000 hour accounts in Csgo.

Anything less than 1000 hours in Csgo is considered new to the game still.

This depends on what you define as in game. According to Steam, I've spent the most time on NGU Idle at 3306 hours, but a large amount of that was spent with the game running while I was asleep or at work. For Steam games with the most hours, I've spent 840 playing Path of Exile but that doesn't include the 200 or so hours playing the standalone client. This is followed up by 440 hours playing Terraria (which doesn't include console version hours), and Realm of the Mad God which I have 325 hours playing.

If we include MMOs in the mix, I've easily clocked 1500 hours playing both World of Warcraft (between Classic and Retail up to and including Mists of Pandaria) and Guild Wars 2 over the years.

Funny enough, I wouldn't include any of these games in a list of my favorite games other then Terraria, so that's good to keep in mind :)

I'd say Final Fantasy XIV, around 4000 hours

1. Doom I and II with who knows how many hours since Christmas 1996.

2. Minecraft since 2011.

3. Binding of Issac with close to 1k hours.

4. Factorio with 850+ hours and currently rising.

Soul Sacrifice

Got around 300+ hours into Borderlands 2 and around 600+ into Warframe

XCOM 2

Hollow knight ~110h

Diablo 2, mostly back in the early days, but resurrected is still fun

MF sorc and Uber killer pally ftw

Minecraft. I spent a lot of time on it, especially when playing with friends on my server.

Terraria and Path of Exile

Guild Wars 2 by far, 10k hours. Followed by Wow and Civ 5.

Planetside 2

10 years and counting

Starport GE

15 years and counting

CounterStrike. Haven’t played in years but there was a while when it consumed my free time.

On steam it's dota 2 with about 3k hours but really my most played game is the old f2p Combat Arms. I nearly exclusively played that game after school to bed for like 4 years, I probably had over 6000 hours logged. Still talk with the friends I made there a decade later.

Swtor

Grim Dawn with 800+ hours. Slay the spire is 2nd with 600+ hours

Team Fortress 2 with over 1,200 hours. I've been playing it regularly for over a decade, so the hours have added up

GTA series in general, and GTA V in particular.

DS1 to DS3, I lost count of the hours.

Any of the Championship Manager games.

I'm at around 1750 hours playing The Binding of Isaac and I'm not done with the game......

Monster Hunter

I racked up about 9000 hours in WoW before quitting, bit over 3000 hours in Runescape.

4000 in arms 3 1000 in TF2 Around 2000 in osrs

Jesus Christ, didn't realise it was that bad. I just wish I was any good at any of them

Nioh 2. The more you play it, the more there is to do

Arma 3 and that is mostly "Escape From" as it's an easy drop in game mode. Although I think I still have way more hours in Europa Universalis 4 but that isn't counted for... reasons.

Also I swear my hours used to be way bigger years ago. I am not crazy right? Like only 170+ hours in TF2 I have definitely played that way more.

Life.

9 months until your game finally goes beyond loading screen. You pay it permanently and cannot stop playing it - and if you intentionally stop playing, you can't play again. No savestates - which sucks for exploring alternatives. You also don't get asked whether you want to play or not as well - you just get thrown in. Also there is no character selection screen and you start with whatever stats, region, context, etc. you rolled.

However, it is definitely quite interesting and gives you really very realistic experiences. Did I mention, that it's much better in its immersion than all the AR/VR stuff and co? You even can properly smell and taste stuff there!