Zelda Ocarina of Time, it was just beautiful and set the standards for many games today. It was huge, unlinear, could do whatever the hell u wanted. Could play for months and not do the main storyline and still have fun. The levels were vast and, for the time, more amazing than had ever been seen in a game, and they were all fun but terrifying at the same time (ok, please remember i was like 10 when i first played this game, the graveyard level was well scary!! :P) ahh... memories :P and its got a fair replay value, ive played through it like 7 times :P For multiplayer.... it has to be Mellee or Mario kart 64, both were groundbreaking in it and are sooo much fun :P