A more recent game which never surfaced in the end, created in 2000, Slither is a simple shooter which promised a lot of new features in the finished game.
Sadly it was never to be, and so the game remained only a simple preview, where you control a ship which avoids attack waves of fireballs.
It is not known how far the game reached before it was scrapped, though hopefully contacts will established what was going on, and what is going on now.
It seems the game may have ever reached this stage, so this is probably it. A shame, as the ideas sounded quite promising.
Not quite slithering onto your C64 screens…