4/5 would have been better if you could have kept your birds after the level was over(raise the prices of birds/upgrades and it would be much more fun, imo).
to everyone having trouble DLing the source file:
right click the link and select "open in new window"(or something to that effect) and the download dialog will appear.
 "VVVVVV Demo"){kind=icon}
 "My Pet Protector"){kind=icon}
 "Crop Defenders"){kind=icon}
 "Shootorial #7"){kind=icon}
 "Shootorial #5"){kind=icon}