CastleMine Free (Version 1.1)
Diffraction Studios
$0.99 / Free
One of the more popular genres in smartphone games are tower defense games. CastleMine takes the standard tower defense formula but adds in a few nice features such as collecting various items during gameplay as well as adding a skill tree which you use to upgrade your towers as you progress through the game. As indicated by the title, it also takes a different approach in terms of how the game is viewed while played - instead of the usual fixed screen or side-scroll, your playing field expands downward into the ground as you protect your Castle.