Zach Gage, who earlier brought us Unify and Bit Pilot, has recently released an iPad-specific musical action puzzler called Halcyon [App Store], a game with a lovely aesthetic and a powerful dose of addictiveness.

In Halcyon, the playfield consists of a number of parallel strings. Along these strings numerous, triangular "currents" of varying color travel towards each other, entering from both sides of the screen. Uninterrupted, these currents will shortly collide with one another. A collision of two like-colored currents will cause them to eliminate each other, while a collision between currents of differing colors means Game Over. The task at hand is to draw a line from one string to another, in such a way as to bridge a current to another of like color, causing an elimination. The play mechanic is somewhat reminiscent of Voxel Agents' Train Conductor.

Accompanying the gameplay is an ethereal, generative soundtrack that you are a part of, thanks to the "strums" you perform while bridging one current to another. It's a scenario that brings to mind�Rez and the various musical action titles that have come since.

The game starts off easy enough, but in short order the difficulty really ramps up. But then so, too, does your understanding of the gameplay. The brief tutorial shows you the very basics, but after a bit of time with the game, you'll come to realize that there's more flexibility to the how's and where's of what you can do than you likely assumed initially, allowing for more complex strategies to be employed. I enjoyed the process of discovery, there.

The core playmode features 36 levels of play through four different environments (basically, differing color schemes, audio tracks, and string arrangements). There are two additional, endless playmodes � Aggression and Harmony � that add some variation to the formula. Game Center and OpenFeint integration drive your competition.

Halcyon is one of those games that's something of a Zen experience to play, but is also downright maddening, both due to the difficulty in the latter levels as well as the "Ok, just one more time!" spell it casts upon you.�I've spent a fair amount of time with Halcyon so far, and I haven't yet made it all the way through. But I can promise you I won't stop playing until I do.