Switchball is an upcoming Xbox Live Arcade puzzle game from Sierra Online and developer Atomic Elbow that makes generous use of physics as you pilot a solitary marble through a series of increasingly challenging levels. We had a chance to try this enjoyable and challenging game out at a recent Sierra press event, which focused on the publisher's upcoming crop of Xbox Live Arcade games.

　　To make it through these puzzles, you'll need to switch up your balls. Wait, can we say 'switch up your balls' on a family Web site?

　　Controlling your marble as you guide it along the path is a breeze. You move the ball with the left stick and can zoom in, out, or around to get a better view of the action. If your ball changes property to become a power ball (more on that in a bit), you can jump your ball into the air by pressing the A button. With the controls down, it's simply a matter of getting from one end of the puzzle, navigating its various puzzles, and finding your way to the end before you zoom off to the next of the game's 30 levels strewn across five worlds.

　　Though you start with your standard default marble in Switchball, as the name implies, you'll be able to change your marble's property as you make your way through the levels. You'll do so in special morph stations that are located throughout the levels, and typically, morphing your ball will be the best (if not the only way) to progress through the rest of the level. Here are a few examples to illustrate the point: In one of the early levels in the game, your path is blocked by some boxes, which your default marble isn't strong enough to push aside. Entering the morph station, you transform your ball into a bigger, heavier form that can easily push aside the boxes. In another level, you need to access areas above your marble. To get there, you'll want to morph into a power ball, which charges your ball up with energy and will temporarily give you the ability to jump into the air. The final form for your ball is the so-called helium ball, one that's lighter than air and can move over cloth bridges that occasionally pop up in the game.

　　The puzzles in Switchball make smart use of the various forms into which you can transform. In one level, you'll need to avoid fans that can blow your ball off the narrow ledge you need to cross; thus, morphing into a heavier form works well here. In another level, you'll use a cannon to blast through various boxes and cross an opening. Many of the puzzles have you creating ledges and impromptu bridges with objects on hand to give you access to new sections of each level. There are also gates you can pass through that act as save points. As long as you manage to get through the save point, you'll restart at the last gate should you fall of the edge or otherwise fail on the level. This is a good thing because, though the game's puzzle start easy, they quickly ramp up in complexity. Many of the puzzles, in fact, will have separate paths that are usually quite narrow and challenging in nature. These paths will let you avoid many of the puzzles altogether, which is perfect for when you're looking to beat your best time on the game's leaderboards.

　　Its heavy reliance on physics and 30 levels--plus an additional six levels for multiplayer co-op fun for up to eight players--take you everywhere from high in the sky to deep underwater. Switchball should be a fun and addictive puzzle game when it's released on XBLA and PC later this year.