.kkrieger

.theprodukkt have developed .kkrieger since mid-2002, using their tool .werkkzeug (from Werkzeug, German for tool). They used an unreleased version of .werkkzeug called .werkkzeug3.

.kkrieger was created for the Breakpoint demo party in 2004. According to developer Fabian Giesen, the code was initially designed with file size in mind by "making it modular, using the right algorithms, storing data in the right way, and so on." The team then removed unused parts of the code and used assembly language for further size reduction. When .kkrieger became playable, it weighed in at 120 KiB and was subsequently shrunk down to 102 KiB. The team then coded their own code analyzer and parsed through the code to ensure maximum efficiency and eliminate the remaining wasted space.

The game won first place in the Breakpoint competition as well as two German game developer prizes at the Deutscher Entwicklerpreis in 2006, in Innovation and Advancement.

Gaming website Acid-Play gave the game 2/5 stars and a mixed review, mainly praising the game's file size, calling it "not a featureless game, but one whose limitations break barriers in terms of what can be done" and ultimately stating that "you'll never find a game which has this much and comes in such a small package."