Suggestions for improvement in a game

Hello everyone,

I am in the process of creating a game similar to ‘Mortal Skies’ Youtube Link : http://www.youtube.com/watch?v=myrXbwpcg8M
You can download it here : https://itunes.apple.com/in/app/mortal-skies-modern-war-air/id351881281?mt=8

As you might have noticed, it is a top down shooter game.

I have been able to implement all the basic stuff such as various enemy types, different types of power ups and the corresponding bullets, homing missiles etc.

I was wondering if you guys had any ideas, like different kinds of power-ups, or anything which would make the game more interesting. Anything you’d like to see added in the game. Perhaps, new enemy types? If you have any such suggestion, please let me know about it. I shall be very grateful.

Thanks,
Manish

How about adding some stories and special missions?