I'm getting sick of this game being the same thing over and over again. Sure it's nice to use all these weapons, but they don't feel much different then the each other, the only weapon that litterely made me say "OH SHIT" is the nuclear anti-virus bomb. But generally this game tops the unforgiving charts in my book. You only get 3 lives, and no continues, and it's a long game, I could only reach the 28th level before I got sick of it, level select really needs to be in the next game, and also just tell us how many there are in total. And every level feels the same, and the spike level with the tail whipping, is just plain unforgiving, face it, the tail whip isn't accurate enough to do a level like that.
Here are some suggestions:
Make the tank have a bigger range of fire.
Make the tank effect enemies (if it did, I didn't notice.)
Be able to destroy the tank (would be epic.)
Go to a level design course.
Get some folder climbing animations.
Get some more variety in weapons.
Make some computer like things hinder, or help your progress (maybe you could use your mouse to help out.)
This game is promising, but it really needs to stop being the same thing over and over again and be different.