This is the unfortunate reality of early access. There is no guarantee of a finished game at all. As it stands, the game IS still being developed. It has been progressing. Slower than any of us (least of all the devs) wanted to see, yes, but progressing.
When the first multiplayer version was released, ZanMgt realized that their existing game engine was not sufficient for the scope and quality of game that they had in mind. They made the conscious decision not to push forward and produce an inferior product (which, as a result of being Steam Greenlighted, still would have made a lot of capital) and have been essentially rewriting the game from scratch.
ZanMgt is not an established game company with reserves of capital. It is not feasible for them to provide refunds in the name of good public relations. Early access funding was not on its own sufficient to continue development. ZanMgt has periodically been carrying out contract work (which takes time away from development) in order to continue developing the game out-of-pocket.
Believe me, nobody is more frustrated with this than ZanMgt and the original backers, but if they'd just given up, published a half-baked game to Steam and abandoned it (as several indies have done), nobody would be getting their refunds or a good game. At least as it stands, there is still hope for a good game.
If you'd like to discuss this further, you can join us in the IRC. Gabriel is (usually) pretty busy working, but if you stick around, he or Aaron should be able to answer any questions you have.