Most improved sequels

[Veknoid_Outcast]

VGPolyglot said:
Street Fighter II. The first one was clunky and is now borderline unplayable, but the second one caused a massive change in the way that fighting games were played, and has many fans to this day.

Couldn't have said it better. This, to me, is by far the biggest gap.

Super Smash Bros. to Melee is a big jump too.