I think that Sonic is remember because yes, he was Sega's mascot, but the Sonic games on the Sega Genesis were all really fun. Heck, I even thought Sonic Spinball was a great game and enjoyed that more than the original! It's sort of sad to see what happened to the series, but I think that people still get very nostalgic when they think of Sonic, and remember those classics on the Genesis and even some on the Game Gear.

NightDragon, that is a good summary. I've been trying to find it, but do you know if the game was bundled with all Genesis consoles or was it an optional bundle?

So I do think 4 million seems like a low number for a game that had a lasting impact on the industry, but if you think about it from the perspective that it was a new ip from a developer that had previously succeeded mainly with ports from their arcade games, it is very impressive. Which gets back to the main point of this thread, why did the game sell so well?

I'm planning on starting the article write up in about 3 hours or so, so get your vote in, and leave a comment with what you think.
Things to comment on
-How much of Sonic's sales were due to bundles?
- How big of an impact do you think the marketing (making Sonic appear edgy) had?
- Do you think that Sonic became a cultural phenomenon with this game, or with later game releases and the merchandise/tv shows?
And any thing else you think had an impact on the games sales.

It was an optional bundle, because at the time they were also selling the Genesis "Core" system package, with no games packed in just the console and controller.  Nintendo also did this too right after the initial launch of the SNES and had the "Super" Set with bundled Mario World and 2 controllers for $199 and the basic "control deck" packaged with one controller like they had been doing with the NES for quite some time for $149 (DAMN my memory's good haha!)

But as far as I know, the Sonic 1 bundle was available for roughly a year right up until Sonic 2 launched, and then it took Sonic 1's place as the bundled game for quite some time, and this was during the peak of the Genesis' popularity, so that's why Sonic 2 was the best selling Genesis game.

It was a great game, and a very good pack-in choice due to the broad appeal of platformers. Another reason I believe is...

Green Hill Zone! It's one of my favourite levels in a game ever, and the only Sonic level that surpasses it is Palmtree Panic, only because it's like Green Hill times ten.

When people first played Sonic (many of who had just upgraded from the NES) they saw the detailed and beautifully coloured background with the stylish checkerboard ground, they heard the rich 16-bit music, and they felt satisfied about their purchase. (too bad Marble Zone came right after)