Ladies and gentlemen, I introduce the most exciting playable game still in development since Minecraft.
Kerbal Space Program.
Build your own space vehicle in a Spore-like building environment, then take on a surprisingly competent physics engine and see if you can get into space and even enter a stable orbit.
There's an incredible amount of content yet to come including missions and hundreds more items to craft into spaceships, but even in its current pre-alpha state it's incredibly fun.
It's free to play at the moment, or you can pre-order it for the low low price of $7US and receive all future updates ala minecraft.
Here's one I'm quite proud of - the HMS Hunteh and its maiden voyage.
Finished construction. Lift off! t+ 30 seconds and the solid fuel boosters seperate from the main rocket. t+ 2:13 and we're in LEO t+ 3:32 and the primary engines - now empty of their liquid fuel - separate from the orbiter. The final rocket stage activates. Speeds now exceed 1221 metres per second. Rolling into an orbit around the Earth. t+ 5:23, and with all fuel spent, the command capsule jettisons and begins the long descent back to Earth. A lot of the graphics are still placeholder, but it's well worth playing regardless. Post your creations!