Rainbow Ninja is a tough game to review, since it is not really much of a game at all. It's more of test of the ability to read words and see colors. It is very similar to one of the games on the Nintendo DS game Brain Age. In that game, a "color" word is displayed on the screen (i.e. "red","green","blue","yellow") and you must say the color of the text, not the word itself. For instance, if the word green showed-up, you would say "blue" into the DS speaker.
Rainbow Ninja takes this idea and boils it down to the most basic game imaginable for the iPhone. The game displays colored color words, and you must press the right circle of color on the interface depending on which instruction is displayed: Press Word or Press Text Color. If it says "Press Word", you must press the color of the word as read.(i.e. Blue would have you press the blue button on the screen,). If it says "Press Text Color" you must press the color of the word as displayed (i.e. Blue would have you press the green button on the screen,).
That's it. If you mess-up once, the game is over. The game counts how many times you get the answer correct in a row. The idea here is to train yourself to make sure you are reading what you are seeing, and seeing what you are reading. While the game is quite basic, it is very addictive. The developer describes the game as both "evil" and "deviously simple". They are correct, as there is no better way to describe it. I personally would have liked to see a couple more variations on the same theme included, because what is here might be a bit too basic, especially in light of some of the other puzzle games we've reviewed on this site for the iPhone. Still, I'm compelled to play this one again and again, even as I mutter "$#@! Evil Rainbow Ninja" to myself each time I restart,