Complex sentence: Versions of the game were completed and reviewed, but not published, for the Amiga and the Sega Mega Drive, with only a demo version for the Amiga being released on two magazine coverdisks.
Split into simpler sentences: Versions of the game were completed and reviewed, but not released, for the Amiga and the Sega Mega Drive. A demo version for the Amiga was released on two magazine coverdisks.