Rather than move blocks around to have them vanish, you'll be tapping on empty squares in the game grid, and if there are matching coloured balls along the column and the row of the tapped square, they will be removed, and your score will be based around the distance apart they are.
The classic mode asks you to reach a specific score on each level before you run out of moves, while easy mode does exactly the same, but removes the timer and reducing the pressure on you to make snap judgements while playing.
The third game mode is the challenge mode with twenty five fixed levels that you need to clear (or clear as much as you can) against the clock to be awarded up three stars for your accuracy and speed in completing the level.
Colour Pop is based around a game mechanic that leaves you a lot of options on the game grid - perhaps too many options for the hardcore gamer, but if you are looking for something to amuse the kids in the family, this free download of a game would be a good addition to your phone, and would naturally fit in well with the Kids Corner utility on Windows Phone 8.
Download the app from the Windows Store, or from the AAWP App Directory.