When it is ready. Thats about the best answer that anybody can give you. From what i understand, the devs want to turn this into more of a game, with real objectives and stuff (right now its still an early alpha basically) before they release it on steam
Yeah. With all the crap, for lack of a better term, floating around in Steam Early Access, a title in that category only has one chance to really wow people and make a great impression, lest it be permanently condemned to the 9th circle of Hell for all eternity by the halfwits that are the (vocal majority of the) Steam community. The ones who have no idea what their machine is (it runs Minecraft/TF2 == "gaming PC") and who leave snide one-liners instead of reviews and post irrelevant tags.
Had a guy try to tell me his PC was great because it runs minecraft on normal settings. My laptop manages that, it has a 1.8ghz dual core i3 with intel HD4000.... I don't refer to it as great (certainly not where performance is concerned anyway, but I guess considering I just needed something for uni work and web browsing while being lightweight while being carried around it is great)