Again...
There really are tons and tons of games like this. Not only like this but almost identical to this one.
I did protected it however, because it is better then many clones out there. The bats flying up and down make it a bit harder.
You could try to add some stuff. For example some "sleepy" bats hanging off the ceiling that wake up and start chasing the chopper if you fly too close to them. And some kind of background music wouldn't hurt either.
Keep improving and next time try to be more original. :)