https://en.wikipedia.org/wiki/EXceed

Developer: Flat software (Tennen-sozai is spun off from Flat software)

http://www.tennen-sozai.com/

Publisher: Nyu Media

https://www.nyu-media.com/

Released in December 2005. Steam version released in 3 August 2012.

Steam trading cards consist of 6 artwork, each with a different character sprite on themed background and game logo at one corner.

Steam profile backgrounds consist of 5 artwork, each with a different character sprite on a black background.

Game has one CG upon completing game.

Game and soundtrack DLC has 11 BGM altogether.

BGM Space Janitor on YouTube by arahman56

arahman's eXceed - Gun Bullet Children OST video playlist on YouTube

https://www.youtube.com/playlist?list=PLL6UrzmB_i56rdHYAaFcRv1j6uDvdKMt_

Full Miyabi Housen gameplay video on YouTube by Felipe Nascimento

Full review of game:

eXceed - Gun Bullet Children - Review (sinicalanimenetwork.com)

Steam store page:

https://store.steampowered.com/app/207370/eXceed__Gun_Bullet_Children/