Puzzle games are one of the best kind of diversions to get your through a boring bus journey. And with Koule, the time will simply fly by.
The concept of Koule is pretty simple to grasp - you need to score as many points as possible by linking five or more balls of the same color in any direction (including diagonally). A piece cannot jump, so you can only move it along a route on the grid where no balls block your way. To move a ball you just click on it, then click the square you want to move it to.
Sounds pretty simple, right? Actually, it's not all plain sailing because the twist to Koule is that after every turn, three more balls are added randomly throughout the ball. So it's a case of making links as quickly as you can so you can leave the board as clear as possible for free movement of balls.
Koule proves to be one of the most absorbing and challenging Pocket PC puzzle games I've tried in a long time. The game is only let down by its weak presentation - the graphics are very plain, the instruction page is messy, and some of the buttons on the user interface don't seem to do anything.
Putting these issues aside, Koule is definitely a recommended way of making those long trips fly by.