I have had this for a few months and have put a few entertaining hours into it (4.7 to be exact). A fun way to describe it would be if Minecraft and Halo had a baby and it grew up playing Starcraft. Unfortunately this is very, very alpha and there is very little to do. Contrary to other comments here multiplayer does work. I would never have been able to complete The Wonky Wonder[1] alone.
It has a lot of potential. I would recommend buying this at reduced price on the basis of what it might eventually turn into however you will be buying into the idea of a game and not what you actually currently get. Whether the devs ever implement all their ideas is another highly speculative manner.
What they plan for the game is infinite, procedurally generated terrain, procedurally generated and modifiable weapons, persistent multiplayer survival worlds, modifiable vehicles and tools, infinitely deformable terrain, highly realistic physics & graphics and a mission / objective based colonization storyline or setting. Only the very minimal skeleton of any of these features are actually implemented right now except infinite, procedural terrain. You can try this out in the latest build but it is very rough, needs obvious work and seems a little bit rushed in to accommodate a community vote on what features players wanted to see.
There are 2 modes of play available right now. There is a very limited 'Creative' mode in which you (and friends) have free reign to run around and build things, though the creative element is limited by the fact you still need to gather resources and craft items. This is the mode in which I believe you will find the most entertainment right now. There is also a Defense mode where you must survive increasing waves of hostiles by building and repairing your base and decorating it with crafted turrets and weapons. Unfortunately both modes suffer with limited replayability as more than about an hours play will reveal the significant bugginess and incompleteness of the existing features. This includes atrocious hostile and turret AI (such as turrets blindly firing into your own constructions, demolishing them), sometimes infuriating hitbox detection for all entities, hilariously over dramatic player pain sound effects, treacly physics and finicky block placement. They recently patched in vehicles and a far improved inventory management and selection system.
It also has temperamental performance and demands quite high spec to be played at its higher graphics settings, even though the difference seems very minimal. It could do with a lot of optimization (it is developed on Unity, if that is a factor at all, I'm not sure) though the last patch vastly improved RAM usage and load times.
If they pull off all their ideas this could be a great game, especially for a multiplayer survival server like situation, ala Minecraft. Unfortunately my sneaking suspicion is that this is the idealistic hobby craft of some optimistic amateur devs that went semi-viral, but that is simply too great in scope to pull off properly without a significant reevaluation of the aims of the project. There simply isn't a game to be had here yet and I believe the dual aims of hyper -graphical and -physics realism will be a hindrance to them implementing a fun sandbox-survival game. For example, the decision to include a fully visible and physically realized body within every player's view means it can get in the way. I have inadvertently twitched my way to a falling death when trying to place blocks below me from a block edge because you can't see past your own legs.
würde gerne wissen wie spielbar oder unspielbar das ganze ist 
Und sie musste jedes Mal ihr eigenes Geschäft wegputzen!
