If the meaning of my username hasn't been made clear, I love the Sonic games. What I'm gonna do now is go through every Sonic game in the main series, briefly tell you what I think about them, and link a couple of music tracks that I like from that game. HERE WE....GO!
Sonic 1: I believe this was the first 16-bit game I've played. It's still a very fun game to this day. Very unique for its time and it's a Sonic game that actually recognises that it's a platformer first, not a "SPEED SPEED SPEED" game first.
Green Hill Zone
Scrap Brain Zone
Sonic 2: Kinda overrated IMO. The level design just isn't as good as what it was in Sonic 1. Too many of the levels could easily be completed by Spin Dashing from the start, then holding right and jumping a lot. Still a very good game regardless.
Chemical Plant Zone
Aquatic Ruin Zone
Sonic CD: One of my favorites. Very unique levels, the time travel gimmick is very cool, and the Japanese soundtrack is probably the best soundtrack of any Sonic game I've played. Plus, the downloadable version is such a steal, buy it right now if you haven't already.
Palmtree Panic Present
Stardust Speedway Bad Future
Sonic 3 & Knuckles: Another one of my favorites. Sonic 3 & Knuckles is packed with cool shit. The levels are huge, every act has its own boss(es), and it's just a lot of fun to play.
Ice Cap Zone Act 1
Mushroom Hill Zone Act 1
Sonic Adventure: This has not aged well. The stages for Sonic and Tails just aren't very impressive compared to the older games and some of the newer games. The other game modes range from OK (Knuckles and Gamma) to terrible (Amy and Big).
Speed Highway
Lost World
Sonic Adventure 2: First Sonic game I ever played. I was hooked the moment I started boarding down San Francisco on a piece of an airplane. The Sonic & Shadow stages thankfully still hold up. They are very refined compared to the levels from Sonic Adventure 1. I could've done without the mecha and treasure hunting stages, but it's good that the gameplay types were restricted to Sonic Adventure's best.
City Escape
Crazy Gadget
Sonic Heroes: I don't like this game. I don't like how the graphics are significantly worse than Adventure 2's. I don't like how bland the levels are. I don't like how repetitive getting everything is. I don't like how bad the dialogue is and how bad the voice actors are, making me want to punch a kitten every time someone opened their mouth. This game just doesn't really sit well with me.
Grand Metropolis
What I'm Made Of
Shadow the Hedgehog: I somehow enjoyed this more than Heroes. I think one of the main things that pushed this ahead of Heroes was that, while this game was also repetitive, you could at least decide what levels you wanted to go to and what objectives you wanted to complete in each playthrough. In Heroes, you just go through the same 7 zones in the same order in each mode, with only slight differences between each one. I also much prefer the hilariously trying-hard-to-be-dark tone of this game over the stupidly childish tone of Heroes. Shadow is still a very flawed game though. The controls are pretty slippery and the Chaos powers clearly needed more testing. As for the guns, I think they worked just fine, even if they are probably the last thing I wanted in a Sonic game. The vehicles, on the other hand, can rot in hell.
Westopolis
All Hail Shadow
Sonic 2006: I haven't played this game. Judging from what I've heard about it and the gameplay footage that I've watched, I'm probably going to keep it that way.
Kingdom Valley
Dreams of an Absolution
Sonic Unleashed: The Werehog gets WAY too much hate. It's very different from normal Sonic gameplay, but that's a very poor excuse for not liking something. Personally, I think the Werehog's platforming was nicely done, and the combat was OK as well. My only gripe is that you can't really control the camera, which can be very frustrating at times. As for the day stages, they're great. They're insanely fast and I love how all the levels are inspired by IRL locations. Now for the real main flaw of the game, what possessed Sonic Team to implement the medal system? The medals aren't exactly easy to find, and you often have to collect a large amount of them to access the next level, it's incredibly stupid.
Windmill Isle Day
Egg Dragoon
Sonic 4: Episode 1: I don't really know what to think of this game. It's not bad by any means, but I don't think the whole concept of bringing Classic Sonic gameplay back worked the way most people wanted. This game just feels like an awkward cross between Sonic 2 and Sonic Rush. Aside from the core gameplay, I don't like the lack of content. Only 4 full zones and a boss rush zone gives this game little substance.
Lost Labyrinth Zone Act 2
Mad Gear Zone Act 1
Sonic Colors: Yet another one of my favorites. This is basically Unleashed, but with everything that was bad about it taken out. What you have left is some really good Sonic gameplay. The Wisps are a pretty nice gimmick as well, adding an exploration factor to the levels without detracting from the main gameplay.
Sweet Mountain Act 1
Aquarium Park Act 1
Sonic Generations: THIS is how you make an anniversary game, developers of Sonic 2006. Generations is an excellent nostalgia trip, filled with all sorts of references to past Sonic games. Classic Sonic plays very closely to the Mega Drive games, and Modern Sonic was just as good as he was in Unleashed's day stages.
Speed Highway Classic
Super Sonic Racing
Holy fuck, this is probably my longest post ever.
EDIT: One more thing.
Go play Eggmanland, then tell me that Unleashed is too easy.