Bonus dungeon, also known as secret dungeon or optional dungeon, is an optional location that is usually much more difficult than the main game with enemies that are much higher level than on other parts of the game. These dungeons are considered sidequests and often contain the most powerful equipment and, sometimes, summons that can only be obtained by completing the dungeon. The boss fought at the end of a bonus dungeon is often a superboss.
A game can have multiple bonus dungeons. Bonus dungeons are common features added to remakes of older games, to give experienced players new material to test their skills against, and to make the remake more lucrative purchase for people who have already completed an earlier version of the game.
Final Fantasy IV
Lair of the Father
CavebahamutmapLair of the Father.
Main article: Lair of the Father
Lair of the Father is an optional dungeon in all versions of Final Fantasy IV where the player can acquire the Eidolon Bahamut. The player can visit the cave as soon as they acquire the Lunar Whale and fly to the Red Moon.
Cave of Trials
The Cave of Trials is a bonus dungeon appearing in the Advance and Complete Collection releases. The dungeon contains eight floors and the final floor contains five weapons guarded by bosses, one for each of the five party members players can swap out. The weapon can only be acquired if the correct member to wield it is in the party. Each of these weapons correspond to the characters who become available after the Giant of Babil to put them on-par with the rest of the group, who can acquire their ultimate weapons in the Lunar Subterrane. However, still stronger weapons can be acquired in the Lunar Ruins.
Lunar Ruins is a bonus dungeon in Final Fantasy IV Advance and Final Fantasy IV The Complete Collection unlocked by completing the game. The floors in the ruins are randomized with ten sets of floors of which the sequence of the sets of floor is fixed. In each set, there are five normal floors and a a sixth gate floor, which contains a save point and a door to each playable character’s challenge, except for the tenth set, which leads to Zeromus EG, a new superboss.
The mobile phone version of Final Fantasy IV has an all new “EX Dungeon”, which is a remake of the Lunar Ruins.
Final Fantasy IV: The After Years
Main article: Challenge Dungeon
Challenge Dungeons are bonus dungeons in Final Fantasy IV: The After Years. Every character with their own tale has one. They become available to explore by talking to Challengingway after the tale has been cleared. The Challenge Dungeons are difficult multi-floor dungeons with powerful enemies and often bosses, but for completing them the player receives a rare item or equipment piece. Challenge Dungeons must be completed multiple times to win all the items they offer.