Gears and Halo xbox 360-> one
Spyro and Crash PS1->PS2
Alot of 4th gen 2D games failed to translate to 3D in 5th gen.

Since my emails were ignored. Here I am, John2290, sick of these weak reasoned and lengthy moderations for saying the wrong thing and a mod team that is doing everything it can to kill this site quicker. So now that I've actually broken a rule instead of mildly hurting someones feelings without even interacting with them, I request my Permban on John2290 and of course this account will be banned. Please and thank you and good luck keeping this site alive while you alienate people with silly moderation.

Tomb Raider - Was already becoming overly pushed in Gen 5 yet was still popular but completely crashed in Gen 6.

Resident Evil - Gen 6 had the series turn itself around when it was becoming too samey and was in decline, RE4 changed not just the series but gaming as well with how third person mechanics were approached Gen 7 the series tanked in quality RE5 was a significant step back but at least was a good co-op game it's with RE6 that the series reached rock bottom as it's seen as not just the worst game in the series but one of the worst in general.

Sonic - Sonic Adventure may not be spectacular but it was a decently good 3D Sonic game in Gen 6 then come Gen 7 it was succeeded by Sonic 06...

Silent Hill - The survival horror that rivaled RE blow for blow even replicating the Gen 6 to Gen 7 fall from grace, yeah I know the room was a PS2 game that divided fans but it's not a bad game or a good one it was an average game that was different from the others.

But was Days Gone good?

Last of Us Part 2

Splinter Cell. Was awesome during the 6th gen. Two releases during 7th gen, Double Agent was good, Conviction wasn’t even a stealth game (Became very action oriented) and we haven’t had a SC game since then.

Fable 3, Perfect Dark (360) and The Last of Us 2. Not in terms of (varying) success but those games were franchise killers for sure.

-The Last of Us. I know it's more an IP than a true series or franchise, considering it only has two games. I don't think The Last of Us Part II is bad, it's an okay game with some redeeming qualities. But it's a large step down from the greatness that was The Last of Us.
-Paper Mario is more of a series within the meta franchise that is Mario. Super Paper Mario was already a step down from the first two games, but it was still great. Then Sticker Star came around and ruined the direction of the Paper Mario games.

3D Mario, from the greatness of 64 in the 5th gen to the underwhelming mediocrity of Sunshine in the 6th.

Man, so much of Nintendo's Gamecube output was a big step down, for me at least.

I don't think Driver has been mentioned yet, so I'll mention it. I've played only the first two myself, but it's obvious from all the reactions that something went wrong when going from the fifth generation to the sixth.