Super Metroid in 2 hours, about 40 some minutes.
Mario 1 in ~6 minutes.
Mario 2 in under 20.
Super Mario World in under 30 mins.
Contra without dieing (not sure how long it took, 15 minutes?)
So I guess the answer is Mario one in 6 minutes, although there may have other forgettable games I beat faster, I can't think of any offhand though.
edit: I can beat star command on the Odyssey^2 in under 1.5 minutes easy.
Super Mario 64 - 36 minutes.
what exactly is sakura doing in you sig...not complaining, just curious
Like falling or something.
she looks like she may be doing somthing else... O.o
Star fox 64 is so short lol... I can't give you an exact time.
I beat Prey in one five hour sitting.
Tic-Tac-Toe in less than 10seconds
Metroid Prime in..err.. 10 hours... so slow...
I dont remember... Thats how fast! lol...
oh wait, i rmember me and my friend would always either play battle tanx: global assault or cruisin' the world every day after school when I was in 5th grade... we would beat it and it took like an hour and a half on each game lol. it was fun
not sure what my fastest gametime was, but i remember beating apocalyptica before it was released when i was still mainly a pc gamer.
SMB3 in 10 min
I'm doubting this. Didn't they do it flawlessly via emulator, slow it down and capture it? It took 11 minutes when they did it that way if memory serves me.
I'm not positive, but I don't think even SMB2 is possible in 10 minutes.
Wario Ware SM, every game all elephants and sound test as well as all multiplayers. In about 2 hours

One of the worse games of all time-Bionicle for the GC.
Beat that in 2 1/2 hours or so.
The worst game of all time. Mickey Mouse and the Magical Mirror. Like 45 to an hour.
It was a bet. If I beat it in an hour I'd get all the ice cream I could eat. If I lost I had to beat it 4 more times. I am very glad that I won!
LoL at Alex.. short game...
I beat Rampage world tour in 12 hours
I beat Wario Ware Smooth Moves.. in like.. half an hour...
Spongebob Squarepants: Revenge of the Flying Dutchman in less than 2 days.