Katakis is a sci-fi shooter inspired to R-Type, developed by Factor 5 and released in 1988 for the Commodore 64 and Amiga. The C64 version was created by Manfred Trenz and Andreas Escher, the two friends that will become famous for Turrican.
Katakis was so similar to R-Type that Activision, that had acquired from Irem the rights to port R-Type to home computers, sued Factor 5 and forced them to stop selling the game. Ironically, Activision was so impressed by the quality of Katakis that decided to ask Factor 5 to develop R-Type for them, in exchange for the permission to restart selling their game. Therefore Factor 5 created R-Type and one year later Katakis was re-released with a new name (Denaris) and a few modified levels.
The story is even more complex than that, since the Amiga version of Katakis was not developed by Trenz and Escher. They didn't have time and resources to do it. Instead they used another clone of R-Type that was developed by some hobbyist programmers. One of them was Achim Moller, that later will take part in the creation of several popular titles.
So, when Factor 5 had to create R-Type, Trenz and Escher developed the Commodore 64 version, but for the Amiga version (the one published by GamesNostalgia) they asked the help of Achim Moller. Amazing.