Great Greed is an excellent R.P.G, with a great story line, it features the usual weapons, spells and armor upgrades found in most modern Role-playing games and uses a leveling up system that builds as you defeat enemys and bosses. There are lots of different villages and people to talk to as the story unfolds, I found the game as enjoyable as Zelda DX and would highly recommend it even by todays standards, it also has one of the best and rewarding end sequences I've seen on the GAMEBOY, the only downside to it is the poor music. Good luck trying to get your hands on it though as it's supremely rare.
