You can buy early access to the game here: Indiedb.com, at a discounted price while the game is in alpha or beta. The full version will be a bit more expensive (not much :) ). You also have the choice to download a DRM free installation file after you have bought early access. The release is currently only for Windows.
The development is going smoothly, and we will try to release new versions once a month. The current version is 1.6.x, and the focus with 1.6.x is to implement more and more features and gameplay. The 1.7.x version will be focused on bug fixing and optimizing. Version 2.0.x will be the first beta release and version 3.0.x will be the final release.
What happens after the final release? We will continue to develop more maps, new stories, fix more bugs and add new features, all included as patches to the final release.