Why is it unstable on Mac and Linux?
It's just that we can't test those builds ourselves. We believe that those versions work fine now. All we are aware of is a little lag issue inside the dragon's cave but that's all. Please report any issues!
So what do you plan to do now that Chapter 1 is out?
First we'll take some time to improve Chapter 1 based on the feedback we've received. Then we'll continue our work on Chapter 2 which will connect the game with the already existing Chapter 3 (Chapter 3 still needs some work but it's 90% done). Then there'll be a huge update in which Chapter 1-3 can be played. Again we'll consider the feedback received. Then we'll work on Chapter 4 and finish off the game.