GoG

Maybe in the future but there are technical issues why its not published on other platforms.

If you refuse steam, just buy it here directly from the website

It's our intention to offer the new version on other stores once it's a bit more fleshed out

Currently there is only the Steam version and the Standalone. The latter is "almost" DRM free, which means it still requires a login to launch the game (or to download updates), but it also runs in offline mode (i.e. if there is no internet connection or if our servers are unavailable).