The object of the game is to "flood" the board with the same color. Starting in the top left of the board, you switch between 6 different colors in order to turn the whole board. The challenge comes from the limitation that you only have 22 "moves" before you fail the board. You can take your time in order to find the least moves needed to flood the entire board, thus enabling score freaks to constantly try to undermine their previous "lowest-move board."
Flood-It! also tracks your lifetime scores so that as you play and complete or fail boards you'll be reminded of your win percentages. Despite this, if you get down to your last color change and realize that you won't be able to clear the board, you can load a new one without penalty to your score tracking. I think the developers did this because you won't be able to clear every board in the number of moves. I could be wrong but there have been plenty of boards that had solutions that eluded me, and I've been playing for some time now on beginner difficulty.
You can also choose from medium and hard difficulty which makes the board larger while also limiting your number of moves so that the difficulty ramps up. The colors are vivid enough that you won't lose your way on these modes, but if your eyes are even mildly difficient you'll have some trouble seeing all of the tiny squares.
I would recommend Flood-It! to anyone based on its ease of play and bite-sized puzzling, plus its free, but if puzzle games aren't really your bag, there are plenty of other time-wasters on the app store.
PLAY READ WRITE / REVIEW SCORE: 3 OUT OF 5