In hindsight, I could have explained some of the game mechanics more. The full game was going to include an old styled instruction booklet, but that should have been including in the demo as well, that's my bad.
Also rebinding keys, that's also going to be added when I work on the game again.
Edit: I've added brief explanations for the crafting and recipes to the game page. Note, you need items in your inventory for these to display anything.