It's a weird setup, but it works. The controls are a little flighty, but responsive, and the physics allow you to do some interesting things while moving around, like catching the edge of a block on a platform, or pushing a ball underneath you. LaMantia said that the plot involves saving the cow that jumped over the moon, but I didn't see any sign of the cow anywhere except the title screen. The stages involve getting your cube to the end of an area, or collecting a certain number of coins along the way.
Because the game is in 3D, LaMantia also plays with perspective a bit. Some stages are played from behind the cube, and some actually rotate the camera as you're playing, switching angles depending on which angle the path in front of you takes. The effect is strange and a little disorienting (the left and right buttons actually move you forward and back when in "third-person" view), but it actually spices up gameplay having to settle your bearings every time the camera changes.
Perhaps because of that, the game is hard. LaMantia said he wants it to be challenging, and I couldn't personally finish one of the four or five stages he showed me. Unfortunately, some of that difficulty is cheap. Sometimes the cube would block my view, or the camera switching would confuse me, making my block fall off of a platform I should have stayed on. But LaMantia is aiming for a "trial and error" approach to gameplay, he said, so he doesn't seem too worried about coddling anyone along. The challenge "makes it kind of fun," he told me.
The game should be out later this month, according to Mantia, and he said the price would probably be one or two bucks. The iPad version will come first, and the iPhone version should offer up some more gameplay later (including the chance, he suggested, to maybe play as the cow). Moon'd looks like an interesting title -- if you enjoy the challenge of an inventive platformer, keep an eye on the App Store for it soon.