Thanks!  I'm having a lot of fun making it!

As for adaptation, each year you are given 2 "Paths" to choose from, each with different events (like battles and markets to buy cards) and an "Animal Bonus" (think relics in Slay the Spire).     So it's up to you how much you want to prioritise finding new cards to change your defenses. 

If you meant moving around your current defenses, they are set once you place them.  So pay attention to what direction invasions are coming from when you choose your "Path" for the year, because you might be stronger from some directions than others.

This is a fantastic question!  And I must admit that I don't have a simple answer for you.  

From playing myself, I can usually think back to one or two bad or greedy decisions that ultimately killed my run.  But each time is unique.  In general, I'd say if I was pinched on a particular resource, my draft was too greedy.  If I had plenty of resources and defences, but I was taking too much damage from battles before the boss,  I didn't prioritize the "mazing" aspect of my island enough.

You made me think about this reply for a solid 20 mins xD.  Great question!  If it's too much to ask, would you mind trying the game yourself and telling me whether you intuitively understand your mistakes?  It would be great if I could find ways to make that easy for players.