Mr Yin & Ms Yang is a simplistic puzzle game based on a neat idea: you control two characters caught in parallel dimensions whose actions irrevocably affect each other's worlds. Unfortunately, while the concept is interesting, the game never strays far enough from its basic formula to keep things entertaining.
The game is based on your two characters. Mr Yin (he's black) can walk on black tiles but treats white space like air. For Ms Yin, however, "white space" is solid ground, but black tiles can be walked through. Both can "flip" tiles on their bottom-right and bottom-left with the tap of a button, changing their color. Oh, and they're sharing the same space; you tap your currently-controlled character to flip between their parallel universes.
The goal of each level is to get Ms Yin and Mr Yang to the same door. To do so, you must strategically plan their paths. Often, inter-universe cooperation in necessary. Later in the game, exclamation-point tiles flip colors on their own when Ms Yin or Mr Yang walk past, while "X"-marked tiles can't be flipped.
For the most part, Mr Yin & Ms Yang is charming, wrapped up in retro, monochromatic graphics and featuring a catchy soundtrack. However, the level designs are what hold it back. Too many of the early levels are easy; I encountered my first stumbling block after the 40th level. To Mr Yin & Ms Yang's credit, you can chose any level at any time; however, there are only 50 levels, so those looking for a challenge will be sorely disappointed.
However, even with its gentle difficulty, Mr Yin & Ms Yang is still a fun puzzling exercise that forces you to reconsider the meaning of "white space." If you just want a simple, relaxing game, give Mr Yin & Ms Yang a look.