The object is to navigate your spaceship, represented by a triangle, through a tunnel without hitting the walls. You steer by tilting the iPhone or iPod touch.
The author says in his app description the game is based on one he used to play on the TI-84 graphing calculator that nearly every high-school student had to buy at one time. Anyway, there have been many variations of this game on nearly every game console starting from the earliest days of video games.
The game is free, so it's hard to grumble about it. It's a shame the developer didn't think it was worth freshening the game with better graphics.
Although it's simple, it's mesmerizing. If you're bored or looking to waste time, this is one way to do it, Orial Ferrer Mesia says.