Which is the game you've played more hours ?

Right Now... In My Steam Library... PATH OF EXILE Has 232 Hours On It.

The Most Time I've Ever Dedicated To Any Console/PC Game In My Life Would Still Have To Be PHANTASY STAR PORTABLE 2 With A Whopping 999+ Hrs Played On And OffLine.

LoTRO. A couple of thousands of hours (mostly before it came to Steam).

Csgo - 214 hours

TF2 512 hours atleast.

Dota 2 with 400+ hours. Next, came Payday 2 with nearing to 200 hours of playtime.

That would have to be Terraria with 374 online hours, plus at least another hundred offline

Fallout: New Vegas - 278 h

The Witcher 2 - Would be somewhere between 200-300. Not on Steam though, I played the DRM-Free ver this much, I got W2 on Steam later.
Oh wait, I have 500 in TF2. Kek.

Guild Wars 2 - over 5k now.

Skyrim 229h

Final Fantasy XI played it since 2004, stopped playing 4 years ago. Played it religiously at least 3 hours everyday for 7 years. So around 7,665 hours not counting time idled while selling stuff etc (In game time was around 21,000 hours lol)

CS:GO - 1663 h

Payday 2, 250 hours on the dot.

CS 1.6 750+ HOURS

1,700h on TF2 here. Also I think I've played like 1000+ hours of Pokémon Diamond.

Dota 2 with 79 hours.
Although if you count non steam games I used to play minecraft all the time. Must have way over 1000 hours on that game. Luckily i'm no longer so addicted to it.

CSGO 881, CS1.6 554,Torchlight 2 366,Killing Floor 337,Terraria 212, Plague evolved inc 141...and much more any games...

Officially, since Steam only tracks you in online mode, mine is Star Trek Online, 970 hours. I finally quit because of all the reasons everyone eventually quit MMO's, and haven't touched it in a year. There's a lot of things I like about the game, but MMO is such a cancerous genre that even its good games grind you into a fine powder eventually.

However I probably put a rough estimate of ~1000-1200 hours into Skyrim that weren't tracked because I was playing in offline mode and I'd be pretty surprised if it wasn't actually my #1 over the Steam timeframe.

I've also probably put about 500 offline mode hours into Civilization V to go with the 120+ that are on my account.

Pre-Steam days I would say (and not sure if with pride or shame) that I'd guess I put roughly 3000 hours into Diablo II. In my defense I played that game for literally a decade, so if you break it down it works out to an average of like 2 weeks each year. But it was something that whenever I got bored with everything else I could always come back to it.

league of legends 488 hours

On Steam it's Infinity Wars with 461 hours

Tetris

EDIT: And this, yeah, yeah, I'm old. On the Steam era, M&B:Warband with 282 h.

Football Manager 2013 - 543 hrs

Football Manager 2013 - 543 hrs

BF Vietnam back in the days and AoS 0.75 also back in the days.

And Tetris forever.