The first 3 weeks will remain free and in the browser, and continue to be updated with final art and such.
Weeks 4 and 5 will be part of the full game, which is paid for. There is no way to pay-gate the browser, so it will be download only. It will be Windows only until fully released and debugged, and then I will look into an Android downloadable.
I am going to try my best to get keys to everyone who has already donated to the game, so they get access for no further cost.