Ichi has 72 levels. I've solved the first 20 or so. There's one thing I don't like about Ichi: on some levels, you must draw a temporary wall. The mechanism for this is annoying. So that's it, I'm abandoning it.
However, the levels I did do - I thought they were well designed and fun. Interestingly, Ichi allows you to make your own levels. So if the 72 provided levels are not enough, you can do some 33,690 other levels produced by other players. Of course, you can make your own levels.
About the graphics: I like the simplistic graph paper look. However, I wish things were a bit bigger/darker & more pronounced.
A few days ago Ichi was listed for free for a limited time. It's now back at $1.99.