I really haven't played most of these series.
Bomberman didn't fall because of Act Zero. It just became less relevant, and now the company is dead.
And really, the games are very samey.
Anyone who honestly thinks Silent Hill became bad is crazy. Yes, it stopped being as relevant and popular, but the quality hasn't dropped in the main series. 0rigins, Homecoming, Shattered Memories and Downpour were all good games.
The problem with some of these, and specifically Sonic, is that the reason some have fallen is because people play one or two games they may not like and they immediately condemn the series and won't buy anymore assuming they're all bad now.
Honestly, of all the Sonic titles, the only ones I did NOT like were Shadow, the DS games and I haven't played, but I have no interest in the Secret Rings game. He's released a lot of mediocre titles, but nothing truly bad. And the only reason Sonic 2006 is so bad is because the story/loading/bugs. The actual game isn't that bad, from what I played.
Granted, this list is about franchises that used to be huge and are now either dead or just not selling what they used to. Kind of like the film "The Artist" with the actor being a huge star until voiced films came along. It's like that.
@Broken_CartridgeThe reason Colors is great is because it was a step closer to the right direction. SEGA was starting to figure out a happy medium for what people wanted. Generations *was* great. It starts falling apart when you get to Modern Sonic's stages in his own eras simply because of his physics, but I honestly loved that game. Except the final boss and how short it was.
@sonic7877Galaxy 2 and Sonic Colors are completely different types of games. I don't even know how you can compare them.
Also, from what I understand, Sonic 4 E.2 wasn't as bad a direction as Sonic 4 E.1.