The way things are going, NASA sending a man back to the Moon doesn't look too likely, at least in the near term. The space agency still wants to give folks at home a taste of lunar exploration, though, and it's released a free game based on that concept. You can grab it right now on Steam.
Dubbed Moonbase Alpha (in what I'm assuming is a reference to Space: 1999), the game has sharp-looking Unreal Engine 3 graphics and rendered versions of actual NASA prototypes:
Moonbase Alpha purportedly offers "20 minutes of play set on a hypothetical lunar outpost." That might not sound like much considering the game's a 1.1GB download, but NASA did get the America's Army folks to develop it. Besides, Moonbase Alpha probably emulates actual space exploration more accurately than, say, Mass Effect. Is it any fun? We'll leave that verdict up to you.