|Babylonian Castle Saga|
|Platform of origin||Arcade|
List of games
There are four games in the main series.
- The Tower of Druaga (1984, Namco, arcade)
- The Return of Ishtar (1986, Namco, arcade)
- The Quest of Ki (1988, Namco, Famicom)
- The Destiny of Gilgamesh (also known as "The Blue Crystal Rod") (1994, Namco, Super Famicom)
In the game's canon, the chronological order is The Quest of Ki, The Tower of Druaga, The Return of Ishtar, and The Destiny of Gilgamesh.
The series is referred to as BCS by fans.
Also, some side stories were made, including:
- The Tower of Druaga Darkness Tower (1996) Namco Museum Vol. 3
- The Tower of Druaga Another Tower (1990's) Namco Museum Vol. 3, Famicom, Game Boy
- Seme COM Dungeon: Drururuaga (2000): Game Boy Color
- The Nightmare of Druaga: Fushigino Dungeon (2004): PlayStation 2
- Druaga Online: The Story of Aon (2006): Arcade
- The Tower of Druaga: The Recovery of BABYLIM (2007): PC 
The Tower of Druaga
The player assumes the role of the hero Gilgamesh, whose goal is to rescue the maiden Ki (カイ, Kai) from the demon Druaga. In order to do this, he must traverse through 60 floors of an immense tower. Gilgamesh comes equipped with a sword, which he can use to defeat monsters, and a shield, which can be used to block magical attacks.
The Return of Ishtar
It picks up where Tower of Druaga left off. The player controls two characters: Ki as well as Gilgamesh. It can also be noted in this game that Ki is a magician, not a damsel in distress like many people believe. The tower now has a few different ways to exit, and the aggregate total of levels is 128 (covering the 60-floor tower).
The Quest of Ki
The story of The Quest of Ki is actually a prequel to the original Tower of Druaga. It occurs shortly after the demon Druaga has stolen the Blue Crystal Rod and taken it to his tower. The goddess Ishtar sends the priestess Ki to the tower in order to retrieve it. The game then follows her doomed quest to the top of the tower, and leads directly into the story of the original game.
The Destiny of Gilgamesh
Also known as "The Blue Crystal Rod", it is the least well-known of the sequels. This game picks up where Return of Ishtar left off and is the final game in the Tower of Druaga series, according to Namco.
The Nightmare of Druaga
This game is set three years after the original Tower of Druaga tetrology. In it, Ki and Gilgamesh are about to be married, however, Ki is kidnapped by an evil sorceress, Skulld. The game is known for its unforgiving difficulty, as death in the game results in losing all your items and half your gold, and its harsh penalty for resetting. Should a player reset the game, they will be greeted by Ishtar, who will scold them for "meddling with the flow of time".
Nightmare was not made by Namco, but by two other companies called Arika and ChunSoft. It was far less successful than the prior games, and was even given a low rating in a video game magazine. This game is the fifth in the "Druaga series" (not counting "Drururuaga"), and the eighth in the aforementioned Mysterious Dungeon series.
Seme COM Dungeon: Drururuaga
This game is placed about 100 years after the original Druaga timeline and stars Gilsh, a descendant of Gilgamesh. Gameplay is best described as a dungeon-building capture the flag with collectible cards. Use cards to equip your character with weapons and spells, and to populate your dungeon with monsters. Then battle against an opponent and his dungeon (AI or link cable). Enter the opponent's dungeon via linked teleporters, find the three keys to unlock the crystal, and return it to your home base before he does the same. Success yields additional cards. Each item or monster is highly specialized, allowing for different strategic combos. Features many Namco cameos, such as Soul Calibur's Nightmare, the sword Soul Edge, Valkyrie, Pac-Man, and even the enemies from Dig Dug.
Druaga Online: The Story of Aon
This game is set outside the main chronology of the series, and borrows characters from Namco's Valkyrie series. Gameplay is similar to The Return of Ishtar, only four players may play at the same time; each controlling one of the four available characters: Gil, a young version of Ki, Valkyrie, or an ancient golem named Xeovalga. Players also earn gold from killing enemies that can be used to upgrade equipment.