The prototype is free for all to play as of now and once you download it, it's yours forever. If the KS has an happy ending, The prototype will start costing money. Those who have the "prototype" reward will be given a key to this prototype and still be able to download it. The prototype will be worked on and updated until September 2020, so in a sense, you get access to "early-early" access during this time. After steam EA release, the prototype will be equal to the steam version. And you will have access to it DRM free on itch, or steam.
So if you want your hands on the game quickly, DRM free and support me a bit more, go for "wall of fame". If you can wait and want to play the game a bit more polished, "despot" is your tier.