Dark Nebula Episode 1 is the first entry in the Dark Nebula series, an innovative, motion-based arcade game in which you pilot a fast-moving disk through short, obstacle-filled levels.
The interface relies entirely on your accelerometer: you tilt your device in the direction you want to move, and the more you tilt, the faster you go. That's it, as you traverse your way up scrolling, vertical levels. You can also touch the screen with two fingers to "calibrate" your device, if you don't want to hold it parallel to the ground.
What separates Dark Nebula from other ball-rolling games is the quality of its execution. In addition to its responsive, predictable controls, Dark Nebula provides a surprising amount of variety in a relatively short game, with challenges that build your skills incrementally. Hazards range from twisty mazes (if you fall off the edge, you lose a life) to spinning blades, laser cannons, and more--all of which will drop your single-use shield or, if your shield is down, cost you a life. You jump from platform to platform using circular boosters (tilting to bend your trajectory in midair), and you have to roll over color-coded areas to unlock corresponding laser walls. None of the puzzles is difficult, but you need fast, precise movements to survive each level--and Dark Nebula scores you on your time, the number of "orbs" you collect (you get an extra life for every 100), and the number of shields you lose. Checkpoints in each of the game's ten levels let you save your progress and recharge your shield.
To top it off, Dark Nebula has an appropriately nebulous backstory, with a carefully rendered industrial backdrop, spacey soundtrack, and occasional hints at the game's premise (including a particularly great final level). Dark Nebula Episode 1 is short but sweet, a satisfying start to a promising series.