X, P, T, and O. What does all this mean? XnO (out now, FREE), a physics-based game by Digital Eclairs. The game opens with a simple tale about two penguins and their friends. With mere letters for names though, it’s hard to keep track of who’s who.

XnOX is a blue penguin who sets off to save his friend, a pretty pink penguin named O, after she’s captured by their enemies. A turtle named T and a friendly puffer fish named P help X.

From the back of a turtle, you’ll shoot X or P at various stacked cans. For some unexplained reason, after you knock all the cans down, O’s cage will open for her to jump out. It isn’t all about good aiming, however. You’ll also have to avoid various moving obstacles, including evil puffer fish. These puffer fish not only float up and down or circle around to obstruct your throws, but also slide forward in rows to bowl X off the turtle if you’re not careful. To dodge the menacing red puffer fish, you’ve got to tilt your device left or right. This, and the 3D targeting, gives a different feel to a game that would otherwise be fairly similar to Angry Birds.

XnOXnO is a lot more fun on the iPad due to the larger screen. The cans can be awfully tiny to aim at on the iPhone, and you can’t zoom in to enlarge the scene. Luckily, the controls feel intuitive. Drag the turtle head about to aim and double tap to toss. Thus, your main difficulty in hitting the cans will come from the obstacles. Watch the puffer fish glare at you if you’re unlucky enough to graze them.

Currently, the game offers over fifty levels. While XnO is free to try, it’ll cost $0.99 (IAP) to unlock the full game.

iFanzine Verdict: Despite a similarity to other catapult games, XnO offers its own unique set of challenges. If you enjoy casual physics games like Angry Birds, XnO is well worth trying, especially for free. Kids will likely love the cute penguins and puffer fish.