What game has taken up the most of your time?

[Zageron]

I'd probably be accurate in saying Ragnarok Online.

I spent at least 4 hours every Monday, Wednesday, Friday, and Saturday, playing KOTH, Devils Square, WOE, and PVP. For about 4 years.

I'd say that would build up pretty quick.
Rough calculation puts it at 3200 hours, holy crap that's terrifying.

Edit: Though I would probably conserve and say that it's more likely to be around the 2000 hour mark.

Edit 2:

And surpassing "games" I've probably spent about 1/5th of the last 9 years on a forum of some kind.