One of the most notable features of Lufia II, an RPG for the SNES, is the Ancient Cave, a randomly generated dungeon comprised of 99 floors which is presented to the player as a side-quest in the town of Gruberik. Every time the player enters the cave, a new layout is generated.
Within the cave, the characters are downgraded to zero experience points and are stripped of all equipment and items. The player must then proceed through the cave's floors, collecting equipment, finding magic spells and increasing levels, with the objective of reaching the Ancient Cave's final floor. There are three ways of exiting the cave: by dying, by reaching its bottom or by finding and using an item exclusive to the cave, named "providence".
Within the cave lie two kinds of chests — blue and red. A red chest contains items which can only be used inside the cave for the duration of the playing session. As soon as the player leaves the cave, all items from red chests disappear with the exception of Iris treasures, rare artifacts that serve no practical purpose, but are displayed in a house in Gruberik. On the other hand, the rare blue chests contains items that are for the most part unique to the Ancient Cave (though not completely — the Catfish Jewel, for instance, can also be won in the battle against the giant Catfish), which can be used outside the cave and can be brought back to the cave on subsequent journeys. The equipment found in the blue chests is often far superior than those found outside of it.