I really like this idea. Needs refinement, but ain't that always the way.
* It's jarring to interrupt the game suddenly to show the purchase screen, the player should have some warning the gameplay is about to change modes. Maybe a progress bar?
* Speaking of progress, telling us what "wave" we're on while we play would satisfy those of us who like progression.
* Purchase prices are weird, how "common" can be more expensive than "rare" or "legendary," and after wave 6 the gameplay stopped to offer me purchases I could not afford, making the interruption not useful.
* The "return" button on the purchase screen is hidden behind the itch.io "View all" "Folow" etc buttons. That's not a you problem that's Itch.
* The game pauses sometimes, I suspect because it's loading a new sound asset just before playing the sound. Maybe Godot needs more hints about pre-loading assets.
Hey, I appreciate the feedback! I'm thinking of making the waves longer overall so the players actually have enough balance to spend and it never feels like an interruption. I'll probably end up re balancing the prices/upgrades as well to fit the new wave length.
I agree that the HUD should provide more info, I'm still trying to find a way to fit the icons on screen because enemies spawn unconventionally at the top of the viewport, which is where most games would usually place their icons and game info. Still working on that point.
Finally thanks for pointing out the bug that Itch.io is hiding the buttons, I'll be sure to fix that for the next update!