We expect to release around a dozen pre-alpha demos up until launch with a demo planned at each major milestones (generally when a new feature has been implemented).
Our first demo; a simple slightly buggy building prototype, is only available on PC but for future demos we'll be opening them up to as many platforms as possible. Beside PC, Mac & Linux we'll be pursuing Xbox and Playstation next, maybe even the Nintendo Switch if 3rd party tools can be optimized well enough. Around the combat demos release, we're hoping to have VR support working on PC.
Check out our IndieGoGo campaign for the latest details!