Shiru's TFMusic Maker is a pretty powerful and relatively easy-to-use tracker that accurately recreates Genesis/Mega-Drive sounds from the soundtracks we all grew up loving, like Sonic 3, Phantasy Star IV, Shining Force, and many more.
The best part about it is that it's totally free:
So if you want to go ahead and make Genesis-sounding music yourself, there's your avenue.
My first full-fledged song with TFMM has just been posted:
Listen to it and tell me how you think I did!