We’ve been busily hotfixing since the release, and 0.6.1 is now much more stable than when it was first released. We recommend downloading the entire thing again:
(Tip: if you extract the latest version directly over the top of the previous one, you won’t lose any of your saved worlds or exported creatures!).
… but if you’re an advanced user and don’t want to download the full 75MB again, you can download the patches. Make sure you apply them in order.