If I purchased one of the previous versions of the game (Monster Island v0.30 to be specific), do I need to repurchase again for the final version?
https://pejoygames.itch.io/monster-island
We created a number of pages, and if you buy through the link above (this page), you will receive all future updates, however you will have to wait for a while.
Looking at the terms in the page title, you'll see that we usually create another page version called "Patreon." It was intended for Patreon backers at first, but we thought, "Why not release it on itch.io so people can play early?"