Mixamonsters is an excellent game for kids that makes use of real life skill where the children learn about colors and what can be created when they mix various colors together. For instance you will be asked to make orange color and for that you will have to figure out which color you must mix to get orange (red + yellow = orange).
If your kid is unable to figure out, he or she can tap on the star button that will give them hints about which colors they should mix. If they are successful, a cute monster appears on the screen. If they mix wrong combinations, the colors fade away and you can then try again.
As you proceed through the game, you unlock monsters and colors which can be use to make more complex shades in slightly tougher levels.
I tested the game on my Microsoft Lumia 535 and it ran flawlessly. The animations and app design is very kid-friendly and it works for all windows phones including the ones with 512MB RAM. I highly recommend getting this game.