3…2…1… And Liftoff … Lift-off the Kerbpallo 11 mission to the Moon.. Hey, are you feelin' a little listless and unmotivated since the end of the space race? Well go iron the wrinkles out of your pumpkin-colored Launch and Entry suit because you’ve just been accepted into the Kerbal Space Program. Available on pc, Mac, and Linux, Kerbal Space Program is a build it and fly it game, now up as in public sandbox mode. It lets you design and kludge together your own launchers, capsules, space planes… …then launch your creation on a mission to low-Kerbin orbit, a Mün landing, or off into some of the deeper spaces of the Kerbol Solar System, the planets Moho like Mercury, Eve like Venus, Dres like Ceres and so on. Building a rocket in KSP is about as easy as snapping Lego parts together… all except for the satisfying click and the tactile feedback and the finding out you're missing the one piece you really, really need. The simplest ship in Kerbal needs only a crew capsule, fuel tank, and an engine… … but more complex vehicles can be built after you've learned the basics. For example, creating separate stages for heavy lifters (like Apollo’s Saturn rockets), is as easy as placing a 'de-coupler' piece between engine blocks. You can cluster together an absurd number of engines and just see how she does! Piloting computers and aerodynamic wings can make your ship fly straighter and make it easier to control. But, whatever you do, don't forget the parachute pack! We couldn’t find everything we wanted to cobble on – there’re no launch escape systems to affect an abort during boost, for example. But the good news is: growing communities of user-developers are designing and uploading cute bits and bobs of custom Kerbal-kit to the sanctioned modding site SPACRPORT. So: Once you've got a rocket stack you're happy with, take it to the launch pad – or the runway, if you’ve built an aerospace plane. Load up your crew of little green vaguely humanoid Kerbals. Then start your countdown; hit the spacebar; and its “onward and upward" as you leave Planet Kerbin behind... Hopefully. Actually flying KSP is maybe the most difficult part. Younger and less experienced rocket-jockeys may need some help getting the hang of the controls. It is, after all, rocket science. You can fully expect your rockets to explode over… and over… and over again. “Blow-ups happen,” as space opera-writer Robert Heinlein said. And catastrophic FAILS are part of the fun of Kerbal, really. Don’t get discouraged: Kerbal Space Program will pinpoint exactly which parts of your ship failed … giving you the chance to alter and perfect your rocket. “Build a little, test a little…” It was ever thus in the space development game. Once you've learned how not to die, you'll quickly graduate to more and more advanced rockets and farther-flung missions. You can send robotic science probes to planets.... Or bootstrap together a large space settlement – module by module – using many individual launches; kind of like an International Space Station program on steroids. But probably the best part about the game is that the learning curve feels totally weightless: Kerbal Space Program infuses you with real physics, engineering and science concepts. You’re getting an effortless dose of aerodynamics, thermodynamics, and orbital mechanics. You'll quickly get a gut feel how much propellant and oxidizer mass is needed to get into orbit… …and how to set-up the elegant orbital arcs required to go anywhere else. Ballistic trajectories and Hohman transfer orbits with perigee burns are all in there, but the game doesn’t force you to study anything. It just flies! Right now, as we film this, KSP is running only a 'sandbox' mode; you'll have to wait for the full version to build an entire space program from the ground level off to the stars. But purchase the game now, and you’ll get all future updates for free. And there's plenty in the game's sandbox mode alone to keep Kerbalnauts flying mission after mission for hours … days … weeks … you may never get ‘em down! Orbiting here inside the Kerbal Space Program, I’m Dave Brody for SPACE.com.