The game I had the most time on was Pokemon Platinum & it was a whooping 734:00 hours, I have since restarted the file so that is as high as it will ever be...

GBA = Pokemon Sapphire = around 300:00 hours, no longer own
GameCube = Super Smash Bros. Melee = don't know the time but longer then Brawl that's for sure, no longer own
Wii = Super Smash Bros. Brawl = 103:06
PS1 = Final Fantasy VIII = 48:19, I need to find a way to start playing this again as my laptop is garbage & won't play it for long without shutting off
PS2 = Shin Megami Tensei : Persona 3 = 238:46, still trying to get all S.Links done without using new game +, it is now easier to do thanks to this file
PS3 = Soul Calibur 4 = 137:19:56, had to cut this off to get a exact timing as it was running as the game was(I know it's suppose to do that, just saying)

Thegame i have the most playtime on is my pokemon platinum game, currently standing at over 970 hours and counting. I have other games but, none even come close to that. Not even Civ IV or supreme commander 1/2 can come close to that on a single round.

Off the top of my head, I have almost 200 hours in Pokemon Diamond. Not sure if thats the most playtime I have on a game, but I'm sure its pretty close.

I broke 250 hours in Heart Gold before I restarted my game. Thats probably the longest single playtime I've had on a game in a long while.

Despite this, I know I have probably lost a good 200 hours of my life to TES: Oblivion and another 200 to Fallout 3, thankfully New Vegas only claimed 60 hours so far.

I've got over 600 hours on Ruby version, and of course sizable amounts on all my other Pokémon games. I have 3 digits of hours each on a myriad of Final Fantasy games, as well. It's just something about RPGs...

From what I know, I have about 200+ hours in my Sapphire Version, about 175 on my Pearl Version. Also, I have well over 150 hours on Spore, which has been slowly taking over my life since 2008.

I haven't been playing Pokemon enough lately to have a sizable amount of hours, but some games with indefinite hours would be Spore (Tons of time spent on that. I'm still running around expanding even though I got to the center a long time ago. I want so bad to eliminate Grox. I'd feel extremely accomplished.), Dawn of War: Soulstorm (I spend about 2-3 hours on each battle, and there's a lot of those battles so it adds up), and Zeus/Poseidon (City building games. Old games, but I still play them sooooooo much).

For me, it's gotta be Pokemon Emerald. I've got about 500 hours on it. Then after that it's probably Fallout 3 and New Vegas. I've got over 300 hours combined on Fallout 3, and about 150 hours on New Vegas. But to put all my games together, I'd say I have at least 2600 hours invested into video games.

Wow, reading this over has told me that I have absolutely NO LIFE whatsoever...
Oh well, back to killing Deathclaws, beating bosses, and completing quests. o3o

I dunno about times--I'm not sentimental about save files and sometimes delete 100% complete ones if I want to start over. I have 824 hours in HeartGold but a lot of them are sidetracked hours spent doing something else while the game was on, or waiting around for rematch calls...

Games I know I've spent the most time playing or have replayed an absurd number of times, though, to the point of front-to-back memorization...
Super Mario All-Stars: admittedly, mostly just 1 and 3--The Lost Levels is borderline impossible and I have this inexplicable inept-ness at US SMB2 and have only ever beaten it once, on GBA, and that was after getting a real game over AFTER DOING A 999-LIVES TRICK
Super Mario World: First game I ever played. I beat the Donut Ghost House on my first try
Super Mario 64
Ocarina of Time: Haven't played the vanilla version since I got Master Quest though
Banjo-Kazooie: on most worlds I can march right in, get all ten Jiggies and 100 notes and leave before an hour has passed--twenty minutes for Mumbo's Mountain. Rusty Bucket Bay, I failed this last time because of a room I actually never knew about that had a Jinjo inside, and Click Clock Wood is just so big that I don't think I'll ever be able to do it.
Melee
Brawl
Pokémon Red and Blue
Gold and Crystal
Paper Mario
Paper Mario 2
Punch-Out!! (Wii)
F-ZERO GX: got everything in it except the Cosmic Dolphin--the AX Cup and every other racer's character video, I have
Dead Rising

Sometimes I wish I could develop that certain bond you have with those games you played all the time as a kid mostly because they were all you had, but now I have so many games I haven't played that it rarely happens.

But then again, I think I've got it for Dead Rising... I've got all the achievements and then some, playing it certainly never gets old. I know everything about it, and yet, I don't; I find something new almost every time I play.

I have 707:08 Hours on my Pokemon Soul Silver. Next would probably be Mariokart Wii with 180:45 hours

I have about 500 hours on Diamond, 400 on Firered, 300 on Sapphire, 200 on Heartgold, and 150 on White. I've probably put in about 300 hours on Super Smash Bros. Brawl.

100th post! Yay!

I'm not exactly sure which, but it's either Pearl or Super Mario Galaxy with about 400+ hours on each.

I have about 300+ hours on HeartGold. But, by the rate that I'm playing Black (230+ hrs), that record's probably gonna change. 500 hours of my life, wasted...

Super Smash Bros. Melee with so many hours I can't look at it because I started over and over since I was around 3 to when Brawl came out. God only knows how many hours I spent on that....