Released in 1994 in Japan and 1995 in the rest of the world, Phantasy Star IV is certainly the finest RPG on the Sega Genesis, and debatably the best game Sega ever created, period.
The game originally began production on the Sega CD, and was planned to feature a return of the first person dungeons from the original Phantasy Star. Alis was also apparently to return as a prominent character, as it bore the subtitle "The Return of Alis". However, the failure of the Sega CD in most markets led Sega to retool the game as a Sega Genesis title, and subsequent rewrites meant that Alis would not return as originally planned.
Still, we ended up with a very satisfying conclusion thanks to some great characterizations, a dynamite soundtrack and an innovative "manga panels" style of storytelling that acted as a nice intermediary between the new FMV technology and the traditional text-based narrative. It also doesn't hurt that, unlike most series finales, it ties up all the loose ends in the plot very nicely and doesn't try to overstep its bounds to become something more than it is - it's just a well told, finely polished game that tops off a great series. Nothing more, nothing less.