About the only game in Steams Early Access program I would recommend to buy is Factorio[0]. It is essentially a factory building/automation game that's constantly getting updated, with one big patch about a week ago and several bugfix versions since. They are also open about their development process, i.e. some devs playing the game live with streamers and answering questions from the streamers and the chat to the best of their ability. In one such instant IIRC they even said they're planning for the 1.0 release towards the end of this year.
All in all, this game is definitely worth your time and money if you're into this game genre.
There's even a demo version if you're not sure.
All in all, this game is definitely worth your time and money if you're into this game genre. There's even a demo version if you're not sure.
[0]: http://store.steampowered.com/app/427520/Factorio/