Could use some work
Definitely needs a shop to buy upgrades. This way if you lose your helicopter and need to steal another one you're actually bummed since you need to buy upgrades again.
If you happen to lose your copter you should have a way for you to continue to climb the tower as a person until you can steal another helicopter.
I think you should implement a money system.
Like for every enemy you kill you get 5 bucks that can be used to buy special weapons or helicopter upgrades.
I'd also like to see a change in background art. Like at 500 points you're in space fighting aliens or something