The following is an excerpt from a conversation in which I explained why Sonic 3 & Knuckles was my favorite game in the original Sonic the Hedgehog games.
S3&K is my favorite and you can suck it. See, I actually played Sonic 1 back in 1991, then Sonic 2, then 3 and then S&K, culminating in the fusion of S3&K; because of that, I enjoyed the growth of the series as it happened, and in that context, “more of the same” was exactly what I wanted.
I was actually playing Sonic 1 just recently and my girlfriend made an interesting remark when I pushed one of those marble cubes in Marble zone; Sonic 1 is pretty much the only game in the series that has that light element of puzzle solving, a hint of the game’s development cycle.
Following that line of thought, I believe that each game brings something unique or has a specific purpose. Sonic 2 was clearly made to be more of Sonic and streamlining the gameplay, while Sonic CD has a much different approach to level layout and of course featured time warping. In a sense, Sonic 3 perfectly follows Sonic 2 in that it gives us more of what made the original great while adding more to the gameplay.