the gameplay hasn't aged particularly well, but for its time, Killer Instinct Gold was fun and had some of the best graphics early in the N64's lifespan.
Goemon 2 sucked ass as far as Goemon games go. The series had a whimper with the 3D n64 game, but has sucked ever since. On topic, I dont even think its 2.5 but Mischief Makers on n64 was very fun despite only being able to use the D pad to move.