I really enjoy puzzle games that you can play for a set period of time and go back to later, like Kami and Toki Tori 2+. Ichi easily falls into the fun, but challenging puzzler category.
If you like "simple" puzzle mechanics (move the ball to pass through all points) that progressively get harder, then you should really enjoy this game.
The aesthetics are nice and simple and make me think of Ballpoint Universe because the background looks like blueprints drawn on grid paper. The music is nice and cheerful, however, I listen to my own music while I play.
The controls are very simple (mouse only) and instructions are given whenever a new mechanic is introduced. The learning curve is minimal, however, the levels get very challenging, and obtaining an "A" grade for each level can be extremely difficult when you reach the later levels.
In Ichi, your goal is to get a ball to pass through a number of points, in as few moves as possible. Initially, all you have to do is manipulate triangles by click the mouse, causing them to rotate - and change the trajectory of the ball when it comes in contact. Spike hazards on the walls are introduced, and you will see new mechanics like the ability to toggle solid triangles with a mouse click, or even drawing lines on the board to change where the ball will go.
You can also create your own levels and play others', greatly adding to the playability.
The game is a great time puzzler and I've added it to my time fillers between games (or just when I want some down time), alongside KAMI.
Very good, challenging puzzle game, grab it if you are interested.