Hello! :)
Great video, congrats! Also, you did SO much in so little time! :o
Regarding the video, I think it would be best to turn down the music volume a little, to make it easier to hear your voice.
Maybe the core stacks should be highlighted somehow. In general, I understand what you explain, but while playing it may be difficult to remember which are core and which aren't.
One idea would be instead of always putting the stacks in the same position (grass in the top-left corner, water top-right...), you could put the core above and the foreigner below. I don't know if that would be a huge code/design change, but I hope not. hahaha
The tiles colors and design looks neat for me, but it may be a good thing to think about color blindness early on, since your game focuses on colors.
About tile design, you can take a look at Loop Hero (in case you don't know already) and how it designs tile combinations. It could help in the fjord problem that you talked about in the video.
The HYPE is still going on, see you in two weeks! :D