The Vacuum Magic llog is here... (Warning: Hungarian language! :)
The Secret (?) Origins of Vacuum Magic
A member called Puzzud at The Linux Game Tome has pointed out that there was another game for the Commodore 64 with a similar gameplay, called "Slurpy".
I used to have a C64 when I was little, but I don't remember playing Slurpy. I tried it when it was mentioned on TLGT, and the gameplay is indeed very much like Vacuum Magic. Granted, there are tens of thousands games out there, and the chance of creating a game that resembles one obscure game is very high.
Puzzud used the word "ripped" to describe this phenomenon, which I find unfair. I don't see everyone knocking all the 10000 shooter games for "ripping off" Space Invaders. Westwood Studios hasn't sued Starcraft's publisher Blizzard for "ripping off" Dune 2. (In fact, Electronic Arts hasn't sued Dune 2's creators for "ripping off" Populous – the list goes on.)
The funny thing is that the controls for Vacuum Magic went through several iterations. At first turning was based on movement (if you moved left the character turned left). This is "normal" for arcade games. This made aiming for the spitting maneuver very hard AND made the vacuuming feel jerky, so I eliminated it in favor of a separate "turn" button. This in turn was very confusing for new players, as the "spit" and "turn" buttons were easy to mix up, and I noticed that even I just pushed both at the same time. After that I merged the two buttons.
- I also experimented with "push left twice to turn left" sort of control, but it felt like double clicking on the mouse: very unintuitive and very difficult while maneuvering between enemies, so I dropped it. So, in the end, basic movement in Vacuum Magic ended up very much like Slurpy. I expect Slurpy went through these iterations too.
I traded a lot of games as a kid, so it is entirely possible that I played Slurpy. I don't distinctively remember the game, but it could be that the mechanic was somewhere in my mind when I started work on Vacuum Magic. Vacuum Magic's gameplay is different: spitting is actually useful, you can eliminate enemies by spitting at them; gameplay is continuous, there are boss fights, multiple players, etc.
On a related note, there's another game that allows you to collect enemies and use them as projectiles. That game is "Zero Wing" (of "All Your Base Are Belong To Us" fame!). Again, the similarity is incidental. I didn't set out to create a Zero Wing copy, but simply came to a similar mechanic.