#99 - Lightweight Port

Animal Crossing (GC) is a direct port of Animal Forest, released for the N64 in Japan. Because of this, the size of the disc is so small it can be completely loaded into the console's RAM, so you can take the disc out while playing and nothing will happen.

SOURCE: http://animalcrossing.wikia.com/wiki/Animal_Crossing#Items_Required_to_Play