I had to take most of the game apart and put it back together differently to get out of the corner I had coded myself into.
I haven't finished putting things back together, but the first two waves are nearly working again.
I have broken the scrolling and collision for the third and fourth waves, so you will probably have to SHIFT to get passed them.
The fifth (boss) level is getting back to nearly working, but I have partially broken the destruction of the ship and level end.
I have also introduce a few crash bugs, so you will probably need to restart!
I'm really only posting this to see what you think of the first two levels and even these have out of control birds!
I'll go back to posting on RS as I get more stuff done, but I fell here works better for gameplay related posts.
http://www.retrosoftware.co.uk/forum/viewtopic.php?f=19&t=909