The music in Sonic blended perfectly with the gameplay and atmosphere of the game. Like the game the music was fast. Each tune had multiple layers to it adding to the complexity of the score. However, the best aspect of the music was how well it blended with the sound FX. I have talked about this before and Sonic is one of the perfect examples of how developers mixed the sounds of the gameplay with the background music. The springs Sonic bounces on, and the rings he collects both have a musical sound to them that add to the music of the game. Since Sonic only has seven zones I can go into a little more detail into what makes them special.
Green Hill Zone: The music here is fast, while at the same time light and fun. It is a perfect intro song that welcomes the player while at the same time sets the fast paced mood.
Marble Zone: The music here is a bit slower. This level does force sonic to stop and preform some trickier jumps. There is also areas in which Sonic has to stop and wait for pillars to rise.
Spring Yard Zone: The music is again a bit slower. In this level Sonic is a bit more out of control because of the abundance of springs. The slower music matches suggests that the player take some time to think before he/she acts.
Labyrinth Zone: Again the music here a little slower. This zone does involve water which slows Sonic down, thus the music matches the gameplay.
Star Light Zone: A night time level, and the music matches the atmosphere. The music is somewhat relaxed but the beat in the background is a little faster then the previous songs.
Scrap Brain Zone: The music is picking up speed again in this level. It is also much more complex then the levels before it. This level throws in new platforming mechanics which require fast gameplay.
Final Zone: The last zone involves almost no running. It is basically a larger boss fight. The music does sound a lot more menacing in this level, which is something that had not been heard in the previous songs. It is a perfect song for a final boss fight.
For better or worse (most likely worse) Sonic inspired game designers just as much as Mario did. And quite like Mario, most games that tried to copy Sonic's success fell flat. Since Sonic was an animal with an attitude and a gimick (speed) every developer tried to get out their own mascot with the same formula. Games came out titled Gex the Gecko, Bubsy (the Squirrel), Aero the AcroBAT, Zero the Kamakazi Squirrel, and countless others. As with any piece of art there are going to be imitators and very few will be worth remembering. Much like how once Walt Disney started making a hit off his creations everyone tried to copy his magic and failed.
It just goes to show how original Sonic was when he came out. Rather than being another Mario clone, the game stood out on its own and gained its fanbase. Sadly Sonic has now become the very thing it once avoided, a hollow mascot. In many ways Sonic is a product of its time. His edginess (in the newer games) now seems cheesy and the games storylines are ridiculous. The bad 90s animal mascots, that Sonic helped influence, have now all died out on other platforms, but are alive and well within Sonics games. But it really doesn't matter how far Sonic has fallen because nothing can take away how great the original games for Genesis are.