This article is from the Final-Fantasy and other Square Soft Games FAQ, by firstname.lastname@example.org (Nick Zitzmann) with numerous contributions by others.
A chocobo from a chocobo village found a magic crystal which made him
become evil, and now resides in a mysterious dungeon. Now, another
chocobo from the town is going to brave the dungeon and find him.
The best way to describe the game would be that it is a Rogue-like game,
complete with magic and summoned monsters. There's also a "forge
system," where weapons can be combined to become more powerful. The
village also grows as the player gets deeper into the dungeon.
This game came packed with a "mysterious data disc" which included cheat
saves for existing Square games and preview videos of some of Square's
other games - Xenogears, Parasite Eve, Soukagai, and more. (A variation
on this disc, without the saved games, was published with Parasite Eve
in the USA.)