Everyone knows that since Sonic games came out in 3D, his reputation has really been falling. So what made the 2D Sonic games so great? This is also research for myself as Id like to make a fangame soon.
The Good
1st - In Sonic CD ts actually a challenge, you dont just have to run from left to right, you need to search around for things, you can time travel, destroy a roboticizer to create a Good Future. Then of course defeat Robotnik/Eggmans machine. Such a simple idea, but harder than it sounds.
2nd - The music really suits the stages. They always have.
3rd - The levels and storylines are original with new and interesting characters, not to mention the different boss machines Robotnik/Eggman brings out all the time.
4th - Its possible to play as Super Sonic anytime during the game you wanted after you got the Chaos Emeralds.
5th - The bosses are awesome especially in all the new 3D games, Perfect Chaos, Biolizard and Metal Sonic.
6th - The difficulty has improved in Sonic Heroes compared to Sonic Adventure.
The Bad
1st - The other games were too easy to complete especially the new 3D games. Not to mention when you could easily defeat the boss as Super Sonic all the time!
2nd - The camera angles change at the most inappropriate time in SA and appartently in the new Next Gen Sonic game.
3rd - There is only one opportunity to play as Super Sonic at the end of the game to beat the huge boss.
4th - There are meaningless missions like in SA Directors Cut. This could be changed to include something more exciting. Same apparently in the new Next Gen Sonic game.
5th - There is basically no thinking involved, its just running fast and jumping at specific times, no searching what-so-ever, except in SA2 with Knuckles and Rouge which is good. Specifically the new Next Gen Sonic game. In SA2 I wanted more boarding like in City Escape!
6th - Its almost impossible to get "A" Rank in battles, like in Sonic Heroes. To get it you have to complete it in like 30 seconds! What?!
These are just a few things off the top of my head.