CodeArt is an iOS app by Pentaquistic Solutions. (According to their website, they are working on an Android version.) For free, you can try to solve 16 puzzles. An extra 99 cents will get you the premium version with 40 challenges.
According to Pentaquistic’s site, CodeArt was designed for children aged 8-10. I agree with that – though I am an adult who enjoyed playing the game. The game could probably be used with younger students fairly easily as long as they are provided guidance.
CodeArt teaches the logic of programming by giving you a design that you must try to replicate with the “code” you are allotted. In the example below (the first puzzle), the target design is on the left. In the orange box, the user must place the commands to make the oval create the same design on the right.
Of course, the designs get increasingly difficult as you proceed through the game, but I feel like CodeArt scaffolds extremely well.