Name this arcade game...

[zektor]

A friend of mine is asking me about a game he used to play at a local arcade, and while I have a vague memory of it, I just cannot place the name. Here is his description:

"It takes place in this circular arena, and you're that little alien in the hovercraft shooting all these monsters that keep coming at you, and when you shoot them, their bottom halves change to other monsters' bottom halves. What the hell is it?"

Any ideas?

[Arcade Antics]

A friend of mine is asking me about a game he used to play at a local arcade, and while I have a vague memory of it, I just cannot place the name. Here is his description:

"It takes place in this circular arena, and you're that little alien in the hovercraft shooting all these monsters that keep coming at you, and when you shoot them, their bottom halves change to other monsters' bottom halves. What the hell is it?"

Any ideas?

Wacko.

[zektor]

That is it! Thanks!