Rite now its my Pokémon Liquid Crystal with the 85 hours I have in it and still haven't gotten all 8 badges but I do have a lvl 100 butterfree . But all time super Mario bros. 2 lost levels its the only Mario game I have beaten in my life and I played it for months upon months straight until it was beaten

Definitely any one of the Mass Effect games. I have hundreds of hours put into each of them and the number is only going to get higher. 

As much as I'd like to say Fallout, it's Mass Effect 3. I spent 30-40 hours in the story, and 296 hours in the multiplayer. The multiplayer was fun

I'm probably wrong, but Trauma Team for Wii comes to mind. I maxed out the time at 99:99:59, so I'm not sure how long I've been playing it.

I have devoted the most time to Pokemon HeartGold Version, totaling in at around 202 hours. No joke!

Minecraft. I have spent thousands of hours over the past few years into this game and I've never tired of it. I'll take a few weeks of break here and there but nothing too long.

Top spot goes to World of Warcraft.  Played from 2006 to 2011 and I racked up over a year of playtime.  At one point I would log in just to log in.  I would sit in Org and do nothing.  I did make a bunch of awesome friends though too.  Before being hooked on WoW, it was Phantasy Star Online Ep: 1 & 2 on Gamecube.  Probably around 2000 hours.

I have probably spent the most hours on Pokemon Yellow, trying to level up my Pokemon and getting them all to their highest stats does take a really long time. It says I have spent 100 hours on it. I don't think I'll ever get bored of it.

I played about one year dota 2 all most every day and I have over 3000 hours of playtime on it. I was so addicted to that game... But now I haven't played it in about 3 months.. And then there are Bethesda games like Fallout's and Elder Scrolls,  When you start to play those games and you really like them it is pretty hard to stop. Gladly I don't play so much anymore so I have time to do something else than just sit in the front of TV.

I bet this is true for lots of you, but you just haven't thought about it: Super Smash Bros. Brawl. Or maybe I've played more Melee? It's gotta be one of those two. I've spent about 300 hours on Brawl (it has a timer) and possibly even more on Melee, even after I got Brawl. But I can't check how long I've played Melee, 'cause my stupid memory card decided to go and corrupt itself.

Hey, I just remembered, I've also spent a huge amount of time raising one of my Chao on Sonic Adventure 2: Battle. Of course, not quite as much as I have spent playing on Brawl.

hmm Pokémon Pearl. I'm a little ashamed to admit it but I have over eight hundred hours recorded on that Pokémon game alone. Second would be League of Legends, I play that game at least once a day and have done so for over a year. Third would be either Skyrim or Runes of Magic. I reached a point in RoM where it takes forever to lvl your toon and I finished most of the major quests in Skyrim.

I devoted a lot of time to playing pokemon x and trying to get a bunch of rare pokemon as well, but I feel as though i have pretty much already done everything I can in the game, so I don't play it as much now. But I still dedicate time to playing games like super smash bros brawl and zelda ocarina of time, any game that interests me whether it is pokemon or something like smash bros or anything cool like that, I get hooked pretty easily and I end up playing it a lot..... 

I spent probably around 300+ hours playing Dragons Dogma: Dark Arisen. That game was just so much fun and had a lot of replay value especially if you're someone who likes to be a perfectionist (like me) lol. I really like games that make you think you're at the "end" of the game but then enters a hardcore mode instead after you beat the boss. Ni No Kuni was a lot like that as well. It breathes new life into a game after you think you've seen it all.

I put a lot of time into Skyrim as well. I think it took me around one week just to explore the entire map, checking every corner as I proceeded. Not nearly as much time as I put into Dragons Dogma though.

Minecraft. I've spent at least 1000 hours playing it and not a day goes by where I don't log on. I've taken loads of breaks from it, but they cancel out with the 10+ hour minecraft sessions I've had in the summer and on weekends.

In fact, I played more than six hours of Minecraft today.

I would probably say Skyrim, or Animal Crossing New Leaf.

I would say Tales of Symphonia on the Gamecube, I got so caught on the story and the gameplay that I finished the game at least 9 or 10 times (not 100%, f*** the compendium quest), which would take me at least 200-300 hours of play time. I even bought the collector edition on the PS3, I'm playing it right now and I'm still enjoying it.
Close to it would be The Legend of Zelda : Ocarina of Time which I can now finish without even try.

      If I had to choose, I would say the Legacy of Kain series. The storyline for these games are phenomenal and begin to suck you deeper into the game itself. The characters of the games are quite interesting and their stories are amazing once you slowly unlock their history within time. The actors they chose for these characters are also amazing. I mean, the voice actors for Kain(or Dumah), along with the actor for Raziel are great. There wasn't ever a time within playing the games that I hated the voice acting. As for the game play, it is smooth and it actually keeps you on your toes sometimes. The atmosphere sometimes can give you the chills, while other times it can build up a sense of anger or other emotions based off of the events that took place. As for the time put into these games, I spend a lot of time finding all of the secrets, all of the upgrades allowed and other great things. For an estimated time, I would way I have played over at least 200 hours or so.

Well, that was fun, I've just spent the better part of twenty minutes looking through all my save files, ever... And the winner is...

Final Fantasy XII. Over 6 save files, I've amassed over 1500 hours of gameplay, sad, I know, and none of these files are duplicates of another, so thats 1500 solid hours, and all of which were approached with differing strategies, the latest file, for example, I'm still in the Barheim passage. and Vaan and Balthier have maxed License boards already, that save alone has 200+ hours, and I've not even unlocked all the characters o,O

Why have I got so many hours? Simply because I'm that kinda nerd who will always, ALWAYS, replay an RPG to see if there's another way it can be done, with most FF games, the answer to that, is no, but you can play some awesome mini-games. Which, sadly, there aren't that many of on XII, barring the hunts, which I've done all of, on one save or another, I also spent forever gathering ultimate weapons and armour, and all the super powerful accessories, all the small trophies for the Phon Coast etc. I'll grab my capture at some point and grab a thirty second video of the load screen and what not.

I would have to say my top time devoted to game would have to be League of Legends I've easily put in over 300 hours (maybe even 400 to 500 hours) into that game..not to mention a little money  Probably after that Pokémon with somewhere in the range of over 250+ hours. After that it kinda falls off below 200 on any games. I'm not always the most dedicated gamer to putting a crap ton of hours into games.