Glass Tower 2 is a physics-based arcade puzzler with some similarities to falling-block video games and the tabletop classic Jenga.
You start each level with a precarious tower of glass blocks--blue ones, which you need to break, interspersed with red ones, which you need to drop safely to the bottom of the screen. You get points for every blue block you break, and you lose points and a life (out of 10 lives to start) for every red block that falls over the side. The challenge comes in choosing which blue blocks to break, and how quickly, as you try to keep the red blocks from teetering over the edge. Later levels also include stationary, unbreakable black blocks and green blocks that you tap to turn blue or red. Glass Tower 2 mixes things up further with occasional "bonus" powers, which you have to quickly tap as they fly up either side of the screen. Bonuses include extra lives, a magnet (which pulls blocks to the center), variable gravity (which you control by tilting your device), and "frozen blocks" (which freezes all blocks for a few seconds).
In addition to its relatively inventive and appealing premise, Glass Tower 2 can also be very relaxing to play, with excellent sound effects and a downtempo electronic soundtrack (or you can play your own music). Unfortunately, this paid app only comes with 15 levels, and you have to pay for additional level packs and a level editor--making it a questionable value as standalone game. Puzzle fans would do well to check out the Lite version before buying.