We completely missed this great finding by Ken Van Mersbergen back last year on the Atari Age website.
Rockball was to be released way back in 1983 by a company called Roklan, and was a conversion of an arcade game that was also unreleased. An interview with Anthony Weber talks about the game here: http://www.ataricompendium.com/archives/interviews/anthony_weber/interview_anthony_weber.html
However, we’re not sure yet if Anthony was the actual developer of the C64 version. The game was never released when Roklan collapsed before it could sneak out. The game itself is a kind of Asteroids clone, but with some nice little features that make it a little bit different than the usual clones.
Ken revealed that he found the game (along with Joust) in the archive of a retired programmer who worked at Roklan. Ken has very kindly provided a CRT image of the game to download, along with a photo of the cartridge that was preserved.
Check this great finding out for yourself and another piece of history preserved.
Contributions: Ken Van Mersbergen