Here's a few little bugbears I have with this fairly impressive game. First and foremost, I don't feel like it's obvious when you're going to hit an enemy. The hit animation will regularly pass right through an enemy, as will the weapon, but it won't register as a hit. Same with some attacks like thrust, where by all rights it should hit, but still doesn't. I don't mean I see miss, I mean it literally won't register that a collision happened, despite it looking like it should.
Second, I like the crafting system, but the UI should be simplified. If you're going to have a recipes window, let me craft from it, rather than going through the entire crafting animation all over again.
Third, if you do a Castaway 3, please make sure you tone down the music, and make it a little less fanfare-ish. While the music was okay, it sounded like Title Music more than overworld music, and got old fairly quick.
Other than these few things, I felt pretty good about the game as a whole. 4/5.
Excellent game. 5/5. My main criticism is that there's no progression for Jack. If you decide to do a sequel, I'd recommend adding some tool upgrades, like to your hammer, forge, etc.
 "Castaway 2"){kind=icon}
 "Jacksmith"){kind=icon}