Clusterball Arcade is the kind of game the iPhone was built for. As you tilt your handheld, it uses the accelerometer to maneuver your ship around the screen. Your goal: collect as many balls as you can before passing through the next ring. More balls trailing behind you equals a higher point total, as well as more seconds added to the clock. However, the more balls you collect, the slower you fly, and each level has a time limit, so you need to figure out the right balance to complete the game's 10 stages. At the end of each level, the seconds remaining on the clock get added to your time limit for the next one. There are multiple levels per stage.

When necessary, you can press one of the brake touchpads on either side of the screen to slow down. Power-ups collected along the way give you various boosts, such as immunity against the obstacles that will damage your ship if you hit them. You'll also come across ramps that temporarily increase your speed. There's a ghost ship option that lets you visually track your current progress against your highest score, so you can follow a similar path. Each level features multiple routes to the end, some yielding more points than others, so you'll want to engage in some trial-and-error if you want to brag about your scores, which you can post on an in-game leader board for the whole world to see.

The longer the tail, the higher the score, but the slower the speed

The controls work pretty well, although sometimes I found myself tilting my iPhone at such an extreme angle to pass through a ring that I had trouble seeing the screen. It would be nice to be able to tweak the sensitivity a bit. It would also be nice to be able to save my progress if I'm interrupted, something that is more common in the handheld world, where many people are playing games during short periods of downtime.

Clusterball Arcade could also use better documentation: the information screen is very sparse, and there's nothing that details the stages, the power-ups, and so forth. Without a reference, I didn't know which power-ups would help me in my current situation, and if I guessed wrong and wound up not completing the level, I had to start over at the first level. That quibble brings up another thing I'd like to see: the ability to retry a level if you fail it, rather than having to go back to the beginning.

Those issues aside, however, Clusterball Arcade is a lot of fun and very challenging. Anyone who enjoys a game that throws down the gauntlet on the first level will love this one. And I imagine it wouldn't be hard to implement fixes for most of the things I've complained about; doing so would certainly make it a more enjoyable experience.