Kerbal Space Program is a multi-genre game where the players create their own space program.
In KSP, you must build a space-worthy craft, capable of flying its crew out into space, without killing them. At your disposal is a collection of parts, which must be assembled to create a functional ship. Each part has its own function and will affect the way a ship flies (or doesn’t). So strap yourself in, and get ready to try some Rocket Science!
Sounds awesome to me! Kerbal Space Program is currently on sale for $23, at a discount due to the heavy development the game is still under.
You can also get a demo from the KSP download page.