I know there's that sentiment sometimes with makers of games that says "Oh, you didn't play through the whole game so if you didn't like it you didn't do it right!" but there's not much fun to be had early on. Grinding is one thing, but it feels like a chore to progress properly even if I do it so I don't feel like it's my responsibility to slog through this thing.
Reason why I stopped playing was because the mechanics are poorly thought out. They work as intended, it's just not that interesting. The whole idea of the castle moving is a neat gimmick but doesn't save the rest of the game. The cannons have to be upgraded to be of any usefulness, as you can't control when they fire and at the start of a match they shoot - often they only fired after I'd cleared a screen of enemies. Arcing shots with arrows wasn't a problem, but having to mouse-over gold to collect it meant that I had to choose between defending myself and upgrading. That, I'm sure, was done on purpose so that eventually I'd run into a stage I wasn't equipped to win and lengthen the game by way of forced grinding. This isn't interesting enough a concept or fun a game to make me want to commit to the grinding upfront, especially when the games I play tend to be winding-down distractions after a 13+ hour day of work. I'm not afraid of grinding, but when the presentation of gameplay makes it to where basically it's my fault I can't upgrade because I can't auto-collect gold like nearly every single other game in this genre is an odd choice.
The beginning tutorial wasn't necessary, really. Instead I'd have liked to see something that actually gave me some descriptors for the upgrades. How much am I powering up my weapons? What is the interval by which I'm shortening the length of time in firing my main and secondary weapons? What exactly do the number-key spells do? Why is all that left out? You obviously had to program those things, why not let us in on the details? I swear to you it won't harm the gameplay experience.
Star rating for the fact that the game basically works the way that it's supposed to, it just still feels incomplete.