I bought my Genesis at Toys R Us during a rare window of time when the price for the Altered Beast Genesis had dropped to $150, but you could mail away for a free copy of Sonic the Hedgehog once it finally came out. It took Sonic several months to get to me, so in the meantime I bought and played through Quackshot Starring Donald Duck. Months later, once the Sonic game was finally delivered, it was in box with the regular box art-- not the "Not for Resale" version.
The games that originally interested me in the Genesis were: Altered Beast, Rambo III, Mickey Mouse in Castle of Illusion, and Golden Axe. I didn't know much about Sonic the Hedgehog at the time, but my friend said it was supposed to be "the best game ever."