Pokémon red, blue, silver, gold or yellow.
spent ages trying to get the Mew teleport/Fly glitch to work....and to get the other one (no name or something, the one from Cinnabar island) to appear. Trying to catch 'em all, aka getting several of certain types for between games trades, getting the random encounters from Suicune.
The list really does go on :]
Oh and trying to get every feature on FF7; including Aeris' lvl 4 limit break and getting the Golden Saucer date with each possible Character [Yuffie, Aeris, Tifa and Barret]
-_-'
XIII multiplayer with friends and bots and beer
Worms 2
any LOZ except PH - which did the opposite. Put me to sleep and I had to charge my DS again >:0
Army Men: Land Sea and Air in No Mans Land
Sonic 2
Super Mario Brothers
Super Mario Land
Super Mario 64
Super Mario anything
Devil May Cry
and the general insomnia provoked by the innumerable amounts of unfathomable fears you get for playing the first Condemned all night.
but mostly pokémon ^^,