[MiS]

My picks would be between Disgaea DS and Elona+, well over 1000 hours on each individually.

Runner-up would likely be MW2 at 800ish hours.

[EXiLE]

Well, let me think...
Ratchet and Clank 2. Easily a few hundreds hours.
Also, probably alot of League of Legends.
and Tekken 3.

[lux]

Isn't life just a game? Therefore, 150,479.786 hours

But for real
1,200 on CSGO.
~3,000 on RuneScape/RSPS
1,500 on MW2
2,000 on Minecraft

[Zephyr]

If over my whole gaming life, probably Battle front 2. I still play it now and again today. 1000 hours +

[Oni]

Probably Garry's Mod, World of Warcraft, Runescape, or Puzzle Pirates. If we are talking PC gaming.

[Nebulous]

mw2. That game was the shit.

[cr33pyguy]

uh officially planetside 2 at around 1400 hours. However I have no record of any form of my hours on minecraft, which I would guess I've spend a lot more on.

[Nyx]

SecondLife: 11 years
World of Warcraft: 5 Years
Runescape: 5 years

You don't have 11 years played on Second Life, or even 5 years on World of Warcraft/Runescape. That's how many years it's been since you started palying them, but OP wants to know how many hours exactly you've played on your top played game.

For me it'd have to be Garry's Mod coming in at 1765 hours. 90% of those hours are DarkRP.

[Losi]

I have about 1200 hours logged in COD WAW on my rrod Xbox 360. It's easily one of my favorite COD's of all time. This was the only COD where I got to the max prestige level. I got about 800 or so hours logged in general on my Steam account. I also have a crap ton of hours logged in the Tekkit and FTB launchers. I used to host a Tekkit server on my old computer, the stuff I used to build was monstrous.

[Techno]

I have approximately 7000 hours logged into Osu. I go hard in that paint.
A few days ago was my account's one year anniversary. <3.