Gravity Sling is the first game to be released from the iPhone Game Jam event held at this year’s 360iDev developers conference in late September. Participating developers were given one night to quickly brainstorm and produce a working game prototype. Gravity Sling was the brainchild of the guys at Riptide Studios, and the result, after a bit of post-event polishing, is a simple and pretty space-themed game that is compelling despite its sometimes shallow and buggy trappings.

In each level of Gravity sling, you need to propel your floating astronaut towards an awaiting space shuttle. This is done by simply picking a destination where you want to aim the astronaut to. A large arrow is shown and adjusts to the changing position of your finger, which represents the desired direction and speed. Letting go sends the astronaut on his fateful journey. Strewn across the various levels, however, are planets of varying sizes that will cause the astronaut to alter course and ricochet around in artistic spirograph patterns. If you gauge the gravitational pulls correctly, your astronaut eventually succeeds in reaching home. Your score is basically the distance travelled, and the longer you can send the astronaut into various orbits before successfully returning, the better. Each successful trip’s distance is logged onto OpenFeint leaderboards, and there are various easily-obtained achievements as well.

All of this works well in Gravity Sling, but sometimes feels like an exercise in trial and error as you can just crash your astronaut quickly and repeatedly in order to find what is often the one sweet spot or zone. Touching the precise area for a massive score is elusive, and there is a stated goal distance for each level, but this seems a bit arbitrary as you are not penalized in any way for finishing a level below the goal. You can quickly burn through the levels if want to simply complete them.

Although getting a super long shot can be satisfying, it can also be a bit dull at times. Gravity Sling’s gameplay is basically fire-and-forget, with no interaction once the astronaut is on his course. A very successful score can have you just looking at the screen for 2-3 minutes, waiting for the astronaut to reach his destination. There’s no way to influence his trajectory or fast forward. Touching the screen at any time starts him on a new trajectory from scratch. The worst is waiting for a long time for what appears to be a good score, only to have the astronaut get pulled into a planet for a crash and burn, Sputnik 1 style. Speaking of crashes, Gravity Sling itself does crash occasionally, the menus can be a little sluggish at times as well, and I have seen the occasional garbled continue screen.

It should be noted that Gravity Sling is one of the first games to use downloadable content as its sole source of revenue. The base game, with 15 levels, is available for free. At this price, everyone should download and try it for themselves. The levels can be completed quickly, and may just hook you into its just-one-more-time core gameplay. An additional 30 level pack is available for 99 cents, which basically offers more of the same. The developer has talked about releasing more levels, as well as a level editor, and has even hinted at some new gameplay elements such as moving planets. The prices have not been revealed, but these additions would definitely expand on what is already a solid app.

Gravity Sling is ultimately a fairly straightforward game that does very well for itself considering its humble Game Jam beginnings. Sir Isaac Newton’s head proved that gravity can be compelling, and this app does a good job in stating its case as well. There is a lot of potential to it that a bit of fine-tuning and enhancing can help reach.