Chopper: Lethal darkness [Steam] is a simple indie game about taking out enemies from an attack helicopter with an FLIR camera.
The developer announced a Linux release this month, with a short one-liner about it being available.
In the game you setup a flight plan picking your route across pre-defined waypoints. Once you reach one, it circles around allowing you to get in on the action. I actually love the idea of these games, but they're never usually all that good.
I'll be honest, at £2.79 you probably shouldn't expect much at all from it. It has the signs of the bargain bin games I used to find in shops like PC World when I was younger. However, the small amount of user reviews it has so far give it a reasonably good look overall.
It also has a DLC to see things from the opposite side, as a gunner trying to take down a helicopter.