Puztas - Simple Addition Puzzle

Puztas is a basic addition puzzle.
Its simple design and one-touch controls make it highly user-friendly.
Anyone can play — you won’t have to add any numbers larger than 10.
Next time you have a few spare minutes, why not give your brain a workout?

▼ The rules:
Trace a path through the numbers and add them up as you go.
You may only move up, down, left, or right.
You can’t return to a panel you’ve already gone through.
You win if your total from start to finish is equal to the number of problems.
There’s even a built-in assistant to help out those who need to brush up on their math.

DEMO:
http://youtu.be/nqktB-iYZAY