Great work recreating that video in game format. if you were looking to improve/change the structure, youtuber Mikan has a similar project
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Oh I've watched so many of these, I think I'm done for now xd
The expanding zone should be easy to change, I just struck a fair balance and didn't bother to iterate. I am still having an idea about optimisations, which I may try for fun. If I do, I may also tweak some thing around. No promises though.
Thank you for kind words!