Take Flappy Bird, that addictive one-button casual game that was typically over in 30 seconds, then add Airwolf (what do you mean, you've never heard of it??!), a terrorist-occupied New York cityscape, missiles and smart bombs, code it using the Unity graphics engine, and you've got the next generation of the genre. The developer overdoes the ads a little, but it's still crazily addictive and hey, he had me at 'Airwolf'....

From the Store description:

With your gunship, save lives. Challenge the enemies. Terrorists invaded the city of New York.

The US military command, sent with your over-armed helicopter rescue the hostages who take refuge on rooftops. Your mission is to save as many hostages. Be careful, if you miss more than three hostages, your mission fails. By cons you'll excuse if you save in more than five in a row.

You should also avoid missiles and enemy aircraft, you have the opportunity to defend you, thanks to your missile launches, you will also weave between buildings.

No prizes for the English then, but you get the idea. You'll also get the idea from the single screenshot here:

You get points for hovering over/past buildings, you get extra points for dipping down to save hostages, and if you miss one you lose a life - and so on. The sound effects are fun, by the way, with cries to get your attention, a big English 'Thank you!' if you pick a hostage up, and a despairing cry if you fail and they bopped off by the terrorists. The addition of missiles and bombs, which you can counter to some degree with your own missiles, aimed at ground launchers just off the screen, mean that a hard game quickly gets impossible, a bit like Flappy Bird.

You can grab this in the Store here. Watch out for the interstitial ads, they're easy to tap on by mistake!