Rainblocks, the second offering from Let's Playing, is a fast-paced, strategic puzzle game which is like a sliding block puzzle in constant flux. Although it only has eight blocks on a three-by-three grid, it gives players plenty of information with which to plan ahead while also throwing enough curveballs to keep them on their toes. This is coupled with the pressure of a timer to make for a game that can be hard to put down but is also good for short play sessions.

The game has roots in traditional sliding block puzzles, which ask a player to reconstruct a pre-defined image by sliding mixed up pieces around a grid with only one open slot. There is one simple gameplay mechanic and one correct goal. The fun of the traditional toy ends, though, once the puzzle has been put together and the strategy is mastered.

Rainblocks uses the basic mechanic of a sliding block puzzle, but instead of trying to put a picture together the player is asked to match pairs of colored blocks (each color marked with different symbols for colorblind friendliness). The target color to match cycles in rainbow order, and when the right color is matched the blocks change color instead of being destroyed. The small playing field is constantly changing, with the consistent order in which matches need to be made allowing the player to plan ahead. Power ups and power downs that appear on the blocks with increasing frequency as the game goes on add just enough spice to keep it interesting. A power up or power down only remains in place for so long, and all but the ones that lock a block in place only activate if you move the block.

All in all, Rainblocks is a tightly designed game. The coding was done by Let's Playing's Eric Koziol, the graphics were done by Dominik Johann, and the catchy music was composed by Manami Matsumae of Mega Man fame. It's a free universal iOS app, supported by unintrusive ads which can be removed for a one-time in-app purchase (the only one the game has) of $0.99.