The goal of this game is simple: rotate two orbs on a circular track to prevent them from colliding with incoming obstacles. Sounds easy? Think again. As a bonus, it only takes one free hand to play this game, so you can use the other hand to comfortably grip the metro pole during your morning commute.
8. ERA TD
This isn't your average tower defense game. ERA TD emphasizes strategy and tactics while also offering a generous number of levels, features, and fighting abilities.
Price: Free on iOS, not available for Android
9. The Room
You come across the box. You solve the puzzle and open it up to find...another box. And then another. This 3D puzzle game challenges you to reveal notes written by a mysterious person by undoing locks that open bizarre boxes. It's clever, challenging, and a great backdrop for a mystery.