Self explanatory..

Over the course of playing on and off for 8 years mine is good old Runescape (4000 hours).

I'm pretty sure it's Minecraft.

Battlefield: Bad Company 2 and BF3, each for some 300-400 hours.

Either Elder Scrolls 3 or Final Fantasy Tactics. Many hundred hour playthroughs for each.

Dang it dude! I had a similar idea for a thread too! >: ) Beat me to it...

Diablo II, probably 2000-3000 hours...

Yeah, pls don't h8, but I played tons and tons of Minecraft with friends a couple years back.

Don't even know how much time I wasted on that sh*t. I spent so much even just walking around while talking on Skype, and would dawdle forever in the early hours of the morning needing to organize my stuff and log off...

Dude, Minecraft is awesome! Who would hate? ; ) I would play that a lot with a bud too, til we beat it together on hardcore. Then we retired it and moved on to Starbound... orz

I would have to say Smash Bros. over it's lifetime. But more recently, I think I've logged more hours in BF4 and Destiny than anything else

Probably Gothic 3. No idea about the hours but 500+ definitely.