When the game starts, the 4x4 grid will be partly covered with primary colors only: cyan, yellow and magenta. You may move a color to an adjacent white cell. Or you may combine it with a like colored adjacent cell. That's good. Or you can combine it with a different color to get a secondary color.
See the blue squares with asterisks? The asterisk signifies that it's a secondary color. If you combine them, they get annihilated. Only secondary colors get annihilated. That's how to achieve your objective.
After you make two moves, a new primary color will pop up some place. Hopefully to your advantage. I played 1 game for over 30 minutes and got nowhere! Why? Because you can line up your colors just right, but that new color pops up exactly where you don't want it.
Finally, today, I solved it! It took 268 moves and just over 6 minutes. I'm very happy!
Oh yes, I should also mention that that was the easiest of 3 levels. The other 2 levels are basically the same, just harder.
Give Colors Mix a try. I need your opinion as to whether it should join the list of Best Puzzle Apps of 2014.