- Bandai Namco
- Sandlot: Creator of D3's flagship series, Earth Defense Force.
- Tamsoft: Creator of D3's other flagship series, the Onechanbara.
- Vicious Cycle Software
Notable works published:
Simple 1500 Series
- Vol. 75: The Double Shooting: RayStorm × RayCrisis — A compilation of RayStorm and RayCrisis
Simple 2000 series
A series of budget games for the PlayStation 2. The name is derived from the fact that they often were simple in design and from price the games were sold at 2000 yen. Arranged in alphabetical order with the most recognizable romanization or translated Japanese title, volume number and any eventual EU/US title.
- Vol. 31: The Earth Defense Force — Released in 2003 in Japan, the game puts you in the role of a soldier in Japan's Kaiju Defense Force to fight off an alien invasion by shooting down gigantic bugs. The game was later released in Europe in 2004 as Monster Attack.
- Vol. 81: The Earth Defense Force 2 — Released in 2005 in Japan and a sequel to The Earth Defense Force. It was later released in Europe as Global Defence Force in 2007.
- Vol.39: Boku no Machi Zukuri: Machi-ing Maker++ — Original published by Media Factory in 2001 before becoming part of the Simple 2000 series in 2003. It was published by Natsume as MetropolisMania in the US and Ubisoft in Europe in 2002.
- Vol.121: Machi-ing Maker 2: Zoku Boku no Machi Zukuri — Released in 2006 in Japan. It was picked up Natsume for a North American release in 2007 and Ubisoft for a European release in 2008.
- Vol. 55: The Catfight: Onna Neko Densetsu (AKA Fighting Angels)
- Vol. 61: The OneeChanbara — Released in 2004, it featured scantly-clad babes hacking up zombies. It was released in Europe as Zombie Zone
- Vol.80: The OneeChanpuru ~ The Onechan Special Chapter ~ — Released in Japan in 2007 as an updated re-release of the original. It was released in Europe as Zombie Hunters (also know as Zombie Zone: Other Side).
- Vol. 90: The OneeChanbara 2 — A sequel to the original game.
- Vol.101: The OneeChampon ~ The Onechan 2 Special Chapter ~ — An updated re-release to the game above.
- Simple 2000 Series Vol. 91: The All*Star Kakutou Matsuri (AKA All Star Fighters)
- Earth Defense Force 2017 — A sequel to The Earth Defense Force 2.
- Eat Lead: The Return of Matt Hazard
- Matching Maker DS
- Onechanbara: Bikini Samurai Squad — Titled Oneechanbara Vortex in Japan. Xbox 360 version.
- Puzzle Quest: Challenge of the Warlords
- Storm Lover - A PSP/PSV Otome Game.