The gameplay is quite simple: link each of the marked tiles either vertically, horizontally, or diagonally without reusing a tile or jumping over any other marked tiles.
And while the concept is simple enough to grasp, this Flash implementation of the game is exceptional, thus proving that execution can be as important as the idea itself.
Everything about this game is polished, from the intro to the interfaces—yes, there are two 'skins' of the game available to choose from. There is even a practice mode available to get familiar with the gameplay before getting started. Once you start a game, a timer counts down giving you 25 minutes with which to solve 25 levels. And if you think you are going to memorize the solutions so that you can whiz through it a second time, you have another think coming: All of the levels are dynamically generated, and therefore every game you play will be unique.
I suggest begining with the alternate interface the first time through. The default skin shows no grid and it may be difficult at first to know when tiles are truly diagonal from one another.
What I would change: the New Game button on both interfaces is too close to the play field. I inadvertently restarted a game after having completed several levels. At the very least, a confirmation dialog is necessary to avoid losing a game in progress.
Also, the small squares that are drawn connecting the tiles as you click is a nice effect, but they serve no useful purpose. I would prefer seeing a thin solid line, begining from the tile I start with, and then connecting each tile in succession. That way I could retrace my steps easily when I needed to restart a level.
Yet another simple idea turned into addictive gameplay through its execution and its interface. Comboling is a beautiful game, and yet it is deceptively difficult. Throw in dynamic levels and a time limit to the mix and what you have is a 25 minute challenge that you can return to time and time again. Click.