Fun game, ended up playing it all the way through after taking some breaks. A few items of feedback:
1. Sometimes right clicking would place my X and then immediately remove it. It seems the input may be firing twice?
2. Even if you mark a spot as X, you can still click on it like normal.
3. It'd be nice to be able to hover over a building and see what tiles are in its scope. When first starting a new zone it can take a bit to process which pieces are buildings or fields. Sometimes I might also not realize that a building is lined up with a far-off island
4. The RNG creates wildly unequal puzzles. Sometimes I'll lose on a harder one and then it gives me a zero-difficulty puzzle. On Final Lands puzzle 15 the first one it generated was trivial, so it was kinda anticlimactic
Very interested to see where you take it