Artillery Live!
Artillery Live! (http://www.gamebrew.com/game/artillery-live/play) is one of the many, many iterations of the classic Artillery game mechanic, which is nearly as old as video games themselves. It was also built in Flash, but there's no reason it couldn't be built in Unity using 3D tank models and some awesome exploding particle effects.
The core mechanic: Artillery games share a familiar mechanic where the player sets the trajectory and power of his shot to demolish the enemy tanks. This version also has a wind speed feature that affects the way the tank shells travel through the air. Over time and in other incarnations, the game mechanic evolved into a pull-back-and-release experience, mimicking a slingshot. Other versions have the gun turret automatically angling towards the mouse, and the player holds down the mouse button to power up his shot.
The skin: The Gamebrew version is a classic tanks-and-mountains affair, holding true to the very first Artillery games developed...
