The most dramatic example has got to be Grand Theft Auto's transition between GTA2 on PS1 to GTA3 on PS2, both in terms of the game design and the growth in fanbase. Same thing could be said about the leap from Red Dead Revolver, a salvaged project based on an over 20 year old somewhat obscure Capcom arcade game that launched on PS2 and Xbox with mediocre ratings and sales, to Red Dead Redemption, which was an international blockbuster with near universal acclaim on PS3 and 360.
Dragon Quest went from VII, which looked incredibly primitive for the time it was released in and one of the more contested entries in the series though I wouldn't consider it bad, to VIII, which was one of the most amazing games of the sixth gen.
Even though they're not strictly speaking the same series, I'm also going to say that we went from Xenogears, which was a flawed but awesome PS1 RPG that was unfortunately rushed at the end because they knew they weren't going to be able to finish, then a big step down to the Xenosaga trilogy, which took all the wrong cues from Xenogears and ended up as a mediocre RPG series with minimal interaction that again ended up having its ending rushed in the third installment, and then a huge leap up to Xenoblade Chronicles, which was one of the most amazing RPGs ever made, my favorite Wii game and one of my top three 7th generation games, done even better on the Switch.
Last edited by SanAndreasX - on 28 September 2020