Space Engineers is a sandbox crafting game in a space setting published by Keen Software House. It offers the experience of building space stations and space ships in a space setting using mined materials from asteroids in a over world. It is definitely more of a sandbox than a game - while the survival mode does offer the vague goal of "don't die" there's nothing beyond that other than crafting.
For it's part, however, the crafting works well, and the blocks all hook together in a visually-attractive and mechanically-intuitive way and the crafting system has a series of complex parts without going into the kind of deep end where you need a wiki to know how to get certain parts. The crafting screens do a good job of communicating the required parts and the construction mechanics as well as deconstruction are both pretty easy to pick up and intuitive. You can arrange the blocks in pretty much any fashion and the game includes things like rotor/stator and conveyor systems for automation as well, and you can construct fully-functional space ships complete with gravity generators, thrusters, and fly around in space.
That is actually the first part where Space Engineers is kind of disappointing to me. Space is a wide and vast expanse with a lot of really interesting things but in Space Engineers even the largest map is comparatively small, and if one were running a multiplayer server with some dedicated friends there is probably a real possibility of depleting all the resources on the map. Furthermore the only space objects you'll encounter are asteroids. There's nothing else. While straight-up planets would likely be unfeasible given the scale that would involve, things like comets, pulsars, quasars, and nebulae are all currently missed opportunities. The tension of trying to survive in the middle of a nebula, or thrill of chasing a comet with your ship are things denied to you right now.
On the creative side, there are a large variety of functional blocks and I've seen both myself and other people create some truly elaborate and fantastic structures with them, such as whole little asteroid colonies or epic space stations. However the fact that there's absolutely no "flavour" items such as beds, recreational computers, monitors, desks, or the like, does make these constructions often feel empty and hollow. As well, the fact that you can't have Oxygen Generation in those kinds of colonies is a bit of an immersion breaker for me. It may not matter to some people, but to someone like me who becomes personally invested in creating that little recreation of something with my space legos, the fact that I can't have a lot of the things I'd like ends up frustrating or at the very least disappointing me.
The survival mode is where the game comes into its own for me, though not having to manage oxygen does take from that a little. The game has an absolutely stellar damage model that has asteroids, stations, and ships deform quite nicely and realistically, and the well-simulated Newtonian physics only add to the spectacle when things do impact. There's a reason there's something of a memetic quality to the game as regards crashes - seeing two ships crash together, or a ship crash into an asteroid, with the damage physics as they are in the game, can be a extraordinarily fun thing to watch.
By the by, it's a fun experience and money well spent, just lacking in a way that I hope gets fixed in the final release, because there is a great game to be had here now, and it can certainly get even greater.