Draw Pac-Man - the sharp angle of the mouth, then his round body - and he'll animate and move off in the direction you drew him facing.
Guide him towards the roaming ghosts by drawing walls in front of him: the direction you draw the wall is the direction in which he travels.
That's the simple premise behind this game, and it captivated the crowds when the DS was first playable at last year's E3. But there's more to Pac-Pix than that.
It's much cleverer than we originally thought. Although stages are essentially a collection of ghost hunts (catch them all to progress to the next stage) many factors complicate that process.
To begin with, there's a time limit, and it gets fairly strict in the latter stages. So you need to create multiple Pac-Men to make your ghost-catching more efficient.
You also have to think about the size of your Pac-Man. Bigger ones have a larger catchment area but move more slowly, so you need a team of screen-filling and speedy Pac-People, working together.
And there's more. The top screen has a little pathway that loops back onto the bottom screen. This area is normally locked, and Pac-Man must hit a switch to get access to the ghosts that are hiding up there.
The top screen also has a number of ghosts floating in unreachable bubbles. These must be burst with arrows, which you draw. They fire off in the direction you draw them and can also be used to shoot at bosses.
You must also draw bombs to break open ghost-trapping blocks. This all creates a number of dynamics that have to be used together if you're going to succeed.
That's quite a lot to think about, and part of the challenge is keeping track of everything that's going on.
The fact that failure on any stage means replaying an entire level again can be extremely frustrating, especially when you're learning how best to approach a situation. But the sheer originality and inventiveness of it all inevitably wins through, making this one of the most memorable games you'll ever play.
Pac-Pix is out now in Japan and will be released in the UK for DS this summer