The gamefeel is fantastic and the action really gets going once you gain a couple of level ups and better item drops.
There's something a little off about the pixel art style in terms of having different kinds of UI elements (especially text) that have a way different scaling to the actual gameplay. The art style is consistent, so this isn't as distracting after a while.
What I'd focus on before release would be to improve the writing. The steam page's top description should point out more about the gameplay and not be a story explanation (write it more like this: "Archtower is an X genre game where you Y and Z"). The in-game dialogue and quest descriptions had a weird tone (a father calling his dead son a loser out of the blue?). You probably want to get a proofreader to go through the whole script before final release.