You can grab Space Engineers for free on Steam right now for a trial period that lasts until 1pm PST this Sunday October 12. If you decide you really like it, it's 40% off until then, too.
Space Engineers is an early access sandbox game about building spaceships, but rather than constructing them in an abstract editor, you have to step into the magnetic boots of an astronaut to weld your creation together, one panel at a time.
Of course, what is built can be destroyed. Space Engineers uses physics modelling to calculate crash physics. If you pilot your creation into a friend's, you'll see those welded panels and modules break off and fly into space in a beautiful spacey slow-mo way.