Having achieved very little progress in cracking the American market with the Sega Master System, Sega's plans for the Mega Drive (renamed Genesis here) were far bolder, with aggressive marketing tactics in place from day one which openly criticized Nintendo and their NES, which, much like Japan, dominated the video game console market. The Genesis launched in late 1989, and although had struggled against the PC-Engine in Japan, quickly eclipsed the US-variant, the TurboGrafx-16.
The early Genesis game library and marketing campaigns in North America focused on the arcade-at-home stance, although Sega also took the decision to create celebrity-sponsored sports titles (as well as the famed Michael Jackson's Moonwalker), a tactic which proved reasonably successful. Sega also partnered with Disney to create platformers such as Castle of Illusion Starring Mickey Mouse and QuackShot, the relationship running for several years into the mid-90s.
Most notably was Sega's strong ties with Electronic Arts, which saw rapid growth on the Mega Drive not least due to John Madden Football. EA stemmed from their history as computer game publishers during this period and turned in to a major player of the video game landscape, eventually becoming the world's largest video game publisher.
The Genesis made huge gains over Nintendo during the console's first couple of years, although for many it was assumed that the successor, the Super Nintendo, would reclaim its crown upon release. Though this eventually did occur, Nintendo's plans were set back dramatically by the release of Sonic the Hedgehog on that day, June 23, 1991, as well as a wealth of high quality titles and strong advertising campaigns depicting the SNES, much like the NES, as the weaker system. Though damaged, Nintendo never truly went away - a number of strange Sega marketing blunders in 1994/1995 and the extended lifespan of the SNES (not to mention the strong support coming from Japan) meant that in the end, the Super Nintendo was able to take a victory.
Sega became disinterested in the Genesis by the mid-90s, focusing instead on the Sega Saturn. It did, however contract Majesco to continue manufacturing Mega Drives in the US through 1997 and 1998, and the few third party developers and first party studios that stayed on board produced games like Vectorman 2 and Sonic 3D - Flickies' Island and many compilations. In an ironic twist of fate, a straight port of Frogger would be the last officially released Mega Drive game released in the country - Frogger had been a series Sega held a license over for much of the 1980s, and coincidentally was one of the last SNES releases in the region too.