Mario World - I forgot how old but we finally got a SNES one June with Mario World packaged in. We played that game to the floor.
Sonic (Genesis and Game Gear) - I traded my hamster at the end of one school year for a Game Gear and that summer was spent poolside with it. Then at night, we'd crash by the Genesis and play the exact same thing (well sort of).
Lufia II - This is just my childhood, period. My brother got it from a friend for his birthday (in August) and we tried to cram as much playtime in before school began.
Legend of Dragoon - I spent the summer before freshman year playing this religiously. I'd eat shaved ice with tea until my face was numb and my teeth were squeaky, all with the other hand on the controller.
Man there are so many more, Mario Kart, F-Zero, Chrono Trigger, some dumb-ass Mickey Mouse game on SNES that was ridiculously fun, Dragon Ball fighting game, Metal Gear Solid, Silent Hill, FFVIII, FFX.
Summers were spent finishing up games our mother wouldn't buy us during the school year. Growing up, my brother and I would be copped up in front of the TV in my mom's bedroom, playing all night after spending the day swimming with super soakers in the pool and roller blading around the neighborhood. And ice cream, lots of ice cream.
I miss childhood

Summers always felt different.
Jam it back in, in the dark.