The blue dot is Your Man. The goal is to get Your Man to the star. Passing over a red square subtracts that number and Your Man must be at least 1 to get to the goal.
Not shown in the images:
White Squares with a red boarder: passing over this square will reduce all the other red squares by that number.
Orange Squares: these are =, <, or > with a specific number.
There are 60 regular levels and at the moment I've done about 40 of them. There are 20 (I think) advanced levels and I've done just 2 of them.
These puzzles are designed with great 'aha' moments. This game is a little gem.