Alright. It's been a while since I've written a proper review, but I think this game deserves one.
Art: 4.5 The style is really basic, but that's to be expected of retro games. However, roaming through levels of nothing but moons, stars, and wormholes eventually became a little repetitive.
Sound: 5.0 Honestly, you could've went several ways with this. Personally, I would have used a more gloomy soundtrack to emphasize that the player is really completely alone. You, however, used this really upbeat (and catchy!) music that really turned the experience around, from a desolate journey through empty space, to a hopeful return voyage to home. Kudos, man. Kudos.
Controls: 5.0 It always takes me a few seconds to get used to the controls in this type of game, but it was simple enough to do so. Still, they were simple and responsive, so no issue here.
Story: 4.0 A simple story that makes me think slightly about a druggie who crashes his car a few miles from home. I know... strange... ANYWAY, it was enough to give the game a purpose.
Gameplay: 4.0 Simple, short, and repetitive. It's the kind of game you'd play if you don't have much time at hand. I can't, however, see much replay value. That's not necessarily a bad thing. Many games on Newgrounds seem to of the "play me once" category.
Overall: 4.5
I understand you wanted a casual experience out of this, but I think you could turn this into something larger, with various dimensions, enemies, and npcs wandering through the mooniverses. Either route you choose, best of luck with your future flashes.