Sonic Screenshot Page 
Here are some screenshots of the most famous Megadrive games series ever produced.
I first played Sonic1 when I was in the USA thanks to a mini-exchange schooltrip kind of thingie.
I was immediately hooked to Sonic, as a fact I'm one of these people who bought a Megadrive instead of a Super Nintendo Entertainment System because of it. Which I didn't regret later on, becuse of the political correctnes of Nintendo. Imagine Mortal Kombat whitout blood and you'll know what I mean.

Warning
This page is almost an exact copy of the Sonic Series page at Genesis Power.
You can download the cartridges there if you didn't already have them.

Sonic The Hedgehog
Sonic The Hedgehog 2
Sonic The Hedgehog 3
Sonic Spinball

This dump came about because of an IRC discussion with  Haze of GeoShock. Haze wrote that when you play the Spinball dumps from the net, "in emulators you get this 'metal' tune... even seems a different length but no cart version of the game anywhere has that music." Snorter happened to have a Sonic Spinball cart, and checking it found that Haze was correct; the cart had a different checksum and some of the music is different. The first noticeable difference in the music is at the title screen. If you have any of the dumps that have been floating around the net, give them a listen and compare. 

Sonic And Knuckles
Sonic 3D Blast
Sonic Classics 3 In 1
This game does not run in emulators, other than to display the game select screen. This is typical of multi-game carts.
Sonic And Knuckles + Sonic 1 (aka Sonic Special Stages)
When you load the game, you will see this screen. Press A+B+C simultaneously to get the game to start.
Sonic And Knuckles + Sonic 2
Sonic And Knuckles + Sonic 3

PREMISE: Who would have thought that a fast-paced arcade game about a smart-alecky blue hedgehog and his efforts at preventing the evil Dr. Robotnik from mechanizing the world would have turned into the hit series that it became? The original is a legend as far as arcade games go, the sequels are for the most part just as good or better, and the venture finally provided Sega with something it desperately needed at the time - a new mascot. Every Sega plaform since has had at least one Sonic game. 

IMPRESSIONS: Colorful graphics, catchy tunes, and fast gameplay are the standard hallmarks of the Sonic series. These titles remain as popular as they ever were, with each new entry adding its own particular twists. The first is a must, and so are most of the others. 

VARIATIONS 

Sonic the Hedgehog (1991, the one and only original, and the game that was most responsible for the popularity of the platform - the Japanese version has scrolling clouds in the background) 

Sonic the Hedgehog 2 (1992, same idea as before but adds a second player-controllable character in Tails the Fox - this was the most successful G/MD title ever produced, according to Video Gamers Online - the beta version, which has been recently unearthed, includes levels that didn't make it into the commercial release) 

Sonic Spinball (1993, a pinball game designed around the Sonic franchise that has all the visual appeal of the platform games, but somehow just doesn't wash - there are two different versions, with slight musical variations being the only notable difference) 

Sonic the Hedgehog 3 (1994, the last in the commercially released series of 2D platformers - not designed for speed as before, you encounter a boss at the end of every level, Sonic was redesigned to give him a more fierce look, Knuckles puts in his second appearance in a Sonic game, and has only six very large stages - the MegaDrive release apparently has some different music than the American release, such as when Knuckles first appears) 

Sonic and Knuckles (1994, Sonic squares off against Dr. Robotnik's newest henchman, Knuckles the enchindia - this employed a special "lock-on" pass-through design that allowed you to plug in Sonic 2 or 3 and play them as either Sonic or Knuckles - you're in for a bit of a surprise if you try using Sonic 1 with it - this is considered by some Sonic fans as the best of the original 16-bit side scroller series) 

Sonic 3D Blast (1996, also known as Flicky's Island in Europe - Sonic travels to the island of the Flickies to save them from Dr. Robotnik - in part inspired by old Sega platform arcade game Flicky - the first commercially released Sonic game to make use of isometric perspective, which takes a lot of adjustment for fans of the series) 

Sonic Classics 3-in-1 (1996, combines the first two Sonic Games and Dr. Robotnik's Mean Bean Machine into a single cart) 

Also released around the same time was Kunckles Chaotix for the 32X and Sonic CD for the Sega CD. As a side note, Dr. Robotnik is known as Dr. Eggman in Japan due to his appearance, and the nickname has been quickly accepted over on this side of "the pond." 
 

Any Genesis emulator should run these ROMs.