Longest game I have played is... World of Warcraft. Started in late The Burning Crusade expansion and hoping to return to the scene in Mists of Pandaria once RL problems are settled with.

I Would happen to Say mine is guild wars .diablo.diablo 2 and Super Mario World I Spended lots of hours on those games even to day  why because their original classics that are really fun an enjoyable

Longest hours on a steam game: Killing floorTerraria
Longest hours on overall game (mostly from childhood):Tales of Symphonia

I played Runes of Magic for about 10 hours a day for two years and that would be the most time I ever spent on a game.

The game I spent the most time on would most likely be my Pokémon Fire Red version which has 700+ hours on it's save file, I love that game and was on a search to find every Pokémon available shiny so...... yeah, a long time and still not finished although they made it much easier to find shiny's in the newer games.  

probably empire total war.
over 100 hours. I dont really play it much anymore but I have completed it many times. a few times as britain, where I actualy gave territorys away just to set up wars(like american independence and napoleonic) and aldo playing as ridiculously small counytrys like the netherlands.
I even modified the game files and played as scotland. that was hard.
my second most would be crusader kings 2, iv got msny hours on that, mostly because its a lot more realistic and tricky than most war strategy games

Mine is likely one of the three of the games here: Team Fortress 2, Pokémon FireRed, or Destroy All Humans. From what I can tell, I have racked up 470 hours in total on Team Fortress 2. For the other two, I really can't say, as my copy of Destroy All Humans for the PS2, along with the memory card that held the data, have long since been smashed by little brothers (v.v) and I had restarted FireRed many times before my dog ate the cartridge (again more sadness). I recently bought another copy of FireRed and racked up 25 hours in no time, but I really don't know how much time I've poured into FireRed or Destroy All Humans, so I guess it could be one of them, but I really won't ever know. 

It will be the never ending game battle of
Warcraft 2 Frozen throne on the Philipipne room
in Garena. If you guys have Garena account add me
my Garena name is Banenzo

The video game I have played the longest would be Grand Theift Auto.The reason why I played it so long is because the main story is insanely long with plenty to do , as well as the side mission s and since I like to get every achievement for a game on Xbox360 that also playex a part in why I played it so long and well also because it was fun.

Super Smash Bros. Brawl. I spent a crap load of time on that. I took at least 1700 hours playing the game, mainly because of how addicting it could be. however, I actually think it's more than 1700 because of how I had 1 copy before but it was too scratched up since I played the game WAY too much.

It's hard telling on what game I have the longest hours because I never even thought about keeping track of my hours on video games. but if I have to say what game I played the longest, I have to say the GTA series, I have started playing it around 2003 and been playing it frequently, so I have to say, the GTA series is the longest I've played.

Probably like Zelda Ocarina of Time or Majora's Mask. One of the two.

Hmm you know how to ask a hard question... Let's see I would have to say there are a few games on that list. I can't really say which one I have played the most, but I have been playing Fallen Sword for 5 years and I log in a lot. If you don't know what that is, its free to play check it out. NO DOWNLOAD YAY. http://www.fallensword.com/?ref=551988]http://www.fallensword.com/player/551988.png Second game on that list has to be guild wars... God I played that day in and day out for like 4-5 maybe 6 years straight. Other then that I play the xbox games Assassin's Creeds a lot. I beat them all about 5x if not more. It's rough but I really like that series. Its intense. I think that is about it.... Ohh wait I forgot my Pokemon Emerald.... God I have playing that ever since it came out... I say I logged more hours in that then any other game I have ever played. I got almost all the pokemon in that. I have 385 all of them at level 100... I am only missing Mewtwo i think or it might be mew... So that has to be the game I played the most. Any way thats my story.