Dept. Heaven is the name given to a series of video games developed by Sting's Product Team A, headed by Shinichi Ito. Currently there are five known episodes, with three already released as well as two spin-off games. JaJa explained in his blog that the numbering system is more of a goal in originality of game design, for example, with Episode II being more original than Episode I but not as much as Episode III.
Episode I: Riviera
Riviera takes place on the floating continent of Riviera. The main character, Ein being a resident of Asgard, is sent by The Seven Magi to rid Riviera of demons and becomes tangled in a bid for the Gods' dormant power through The World Tree.
Riviera is played almost as a visual novel, with "triggers" on each screen that can be selected, rather than directly controlling the movement of Ein. In battle, Riviera plays out similarly to the RPG stereotype, however aiming and attacking requires much more careful control, due to the lack of an explicit ability to decide the target of an attack, and the fact that all but one item have a limited amount of uses.
Riviera focused very strongly on the story and character interaction, even going so far as providing the player with the opportunity to slightly affect the ending by developing stronger relationships through his actions with particular female members of the cast.
Episode II: Yggdra Union
Yggdra Union takes place on an unnamed continent. The game chronicles the Yggdra War, where the Bronquian army begins a brutal rampage throughout the world, conquering territories until Princess Yggdra Yuril Artwaltz, of one of the conquered countries, rallies against them.
The game plays differently from most Strategy RPGs, in that you have some amount of control over the battles you would typically just watch. In these battles you can activate cards and control your units' attack strategies. Another unique aspect of the game is that the on-map formation of your units is very important, creating the eponymous "Union" system that is vital to victory.
There are two spinoffs to this Episode, Yggdra Unison and Blaze Union. Yggdra Unison is an alternate-universe retelling of the main game with twelve possible protagonists; Blaze Union is a prequel to Yggdra Union taking place in Bronquia three years prior.
Little information has been revealed regarding Episode III, except that it is currently planned to be a PC MMORPG.
Episode IV: Knights in the Nightmare
Knights in the Nightmare takes place in Aventheim, a world recently interrupted by the invasion of a demonic army. The player leads the Wisp through the story, unraveling the past through the events of the present, in order to save Aventheim.
The game plays like Chess infused with RPG and shoot 'em up elements. The player moves the Wisp around using the touchscreen, activating attacks on allied characters and avoiding screen-covering shots from enemy characters.
Sketches for a new game began appearing on JaJa's blog, eventually being stated as belonging to DHE IX. Little information aside from the sketches has been released, but it will have geographical and day and night mechanics and be a fully 3D game, a first in the DHE series. The current goal is an end of 2010 release.
In the unveiling article for Knights in the Nightmare, it was explained that the worlds share a common Asgard, but no further details on their relations were given. In a later Dengeki Maoh article it was revealed how each game interacted in the Universe, each initially taking place on the overworld and being connected in some way to either Asgard or the Underworld. More connections were revealed when Knights was finally released, in particular with the release of the Dept. Heaven Episodes World Guide and a thinner American version, The Tome of Lost Souls. These releases explained the various connections between the games and further delineated the culture and history of the universe in which they took place.
Many gameplay connections can be derived, from the limited item use mechanic appearing in all the games, to the retry functionality allowing the player to continue the story even if the game is too difficult for them. JaJa explained on his blog that the numbering of the series has more to do with how original the game is than anything else.
Product Team A
While only expressly tied to the series starting with the announcement of a series, the development team seems to remain relatively consistent between games. Artist Sunaho Tobe and lead designer Shinichi Ito have both been involved in all three currently released episodes. Other artists involved with more than one episode in the series include Yoshinori Iwanaga and Satoko Kiyuduki. Shigeki Hayashi has composed music for all three released episodes, working with Minako Adachi on two of them.