The first 'Final Fantasy' title on the Game Boy, Legend allows you to choose from 8 different characters, from the usual human male or female to zombie, wererat, redbull (not the drink), clipper or mutant male or female. No matter which you choose, the goal stays the same: Increase your experience points and abilities by defeating many varied enemies through-out the land.
Much like the FF series of old (and new), you can choose members to join your party and the quest that lies ahead (either warriors, mutants or creatures). Every character has a limit to the amount of moves available during every battle and experience points are gained after each fight, increasing stamina, power, etc.
Despite bearing the name of Final Fantasy, the game, whose original name is Makai Toushi SaGa, is considered in Japan a part of the SaGa universe. The game is indeed much closer to SaGa games than to Final Fantasy ones, featuring separate stories of different characters and focusing on gameplay more than on plot line.