There may be a debate at some point in the future of iPad game development as to whether ports — App Store-ready copies of games that were originally developed for other devices — do more harm than good for the “revolutionary” tablet computer. After all, Apple has emphasized the iPad’s unique interface and challenged developers to create software that’s truly optimized for its hardware, suggesting that duplicating what’s come before devalues the “magical” capabilities of the device. And to some extent, it’s wise to push developers towards totally new and innovative games. But the puzzle game World of Goo ($10, version 1.0) from 2D Boy makes such a compelling counter-argument that we’d expect any debate to be a long way off: ported from the two-year-old PC, Mac, and Wii title, it is a complete, console-quality game that is for the most part improved merely by shifting its controls from mouse or joypad to swiping and tapping.

Like so many other App Store releases before it, World of Goo is a physics puzzler, relying upon you to build structures while taking into account obstacles, elements such as water and wind, explosions, and machines of various sorts. But 2D Boy’s dystopian theme, interesting play mechanics, and 46 bona-fide individual levels set it apart from anything seen on the iPad before.
Each side-scrolling level requires you to help balls of goo escape from an entry point to an exit at some seemingly unreachable point a screen or three away; you drag the ever-moving balls one by one to form structures that enable at least some of the goo to reach a pipe or other exit where it can survive. Different colors indicate different types of goo, some capable of forming temporary or complex structures, and others creating permanent and simple ones, while still others serve as balloons or appear as disassembled components of larger, head-shaped balls. You complete a level by rescuing a set number of balls, and earn bonuses by exceeding the minimum or meeting an “OCD” level—effectively, by saving every possible ball without having overbuilt the rescuing structure.
The levels are so diverse and interesting that the game doesn’t get old, and there are so many of them, individually novel, that you will easily spend hours if not days playing through the game. One challenges you to build a bridge over a saw-like windmill on a blustery day; another sees you pushing a huge goo face up a pipe and into a grinder where it will become face cream. The goo balls are animated smoothly, including fluid simulation elements that only rarely become obviously polygonal—something that could have been improved a little—and the backdrops are so gorgeously conceived, alternating between colors and shadows, that earlier “everything’s on sketch paper” physics games look primitive by comparison.
Here, each stage is illustrated with elements that could have come out of angsty painted cartoons, while equally beautiful but generally melancholy music suggests a sad toil for the goo balls as they wait to be rescued by you; signposts in each level serve as comedic hints as to what you’re supposed to do, and occasional intermissions briefly advance the story or provide comic relief. 2D Boy wisely doesn’t weigh the game down with exposition or trap you behind tutorials; you learn naturally as you play and ask for help when you need it. Fireflies (“Timebags”) appear occasionally to let you backtrack from mistakes a limited number of times; you’ll certainly have to restart later levels once you’ve experimented enough to figure out more optimal solutions.
If there’s anything imperfect about World of Goo, it’s a consequence of transitioning from a pointer-based interface with pixel-sharp precision to a touch-based interface with multi-pixel imprecision: the ever-moving goo balls overlap one another on small structures, so picking the right one of two or three overlapping balls—say, a green structural goo or a pink balloon goo—depends on the game to make a choice as to what you’re trying to select, and it’s not particularly good at reading the player’s mind. Similarly, floating name and height labels are introduced during a bonus mode that enables you to build a structure with all of the bonus goos you’ve rescued. The labels grow in size when you tap them to become more readable, but there are so many of them in small spaces, again overlapping with the goo balls, that selecting imprecision grows and building becomes frustrating.