This is more fun than I thought it would be.
I know this is still in development, but I have some suggestions if you're interested. You've probably already planned some of these for future versions.
• The crank could handle piece rotation, in addition to B.
• Matching graphics styles for the knight scene and playfield. I think changing the playfield graphics could enhance readability. Sometimes, it's a little hard to tell how much space the various items take up.
• Permanent scoreboard.
• I keep thinking about if there's a way to have more interactivity with the knight scene. Like, if you successfully make a 5x5, the knight encounters a bigger kind of enemy that takes more hits, giving the player a little more time before the next item drop. High risk/high reward, beyond just points. Something like that. Or different kinds of items: Potions, weapons, armor, etc. Make squares using all one kind of item, and the knights behavior changes in some beneficial way, adding another element of strategy. I don't know. Maybe these ideas push the game too close to Inventory Hero.
Anyway, cool concept : )