I designed a game called Destructor that was essentially aimed at the Mobile platforms. The concept overview is as follows
The primary mechanic in Destructor is the “destruction” of one’s own tiles. Whenever a player destroys their tile they capture all of the surrounding tiles whether they be neutral or player-owned.
If the destroyed tile was touching an empty space where a previous tile had been destroyed, then that space is converted into a new neutral tile.
There are three stages in a tile’s life: neutral, captured, and destroyed. Neutral tiles get captured, captured tiles get destroyed or captured again, destroyed tiles turn into neutral tiles again when an adjacent tile is destroyed.
The player can also have access to a variety of different power-ups in the form of Power Cards. These can drastically alter the flow of the game.
There are different kinds of objective-based game types to choose from.
The whole design document in its original incomplete form can be found here.