Really nice job! I had a small bug where the right and top borders of the arena was out of my screen, the game went smoothly but I couldn't see the full box.
Love that you included a quit button, a surprising amount of games on itchio force you to task manager out so it is much appreciated.
Most things work as intended, however I'd be wary of edge case bugs like opening the shop and pause menu at the same time, it's not game-breaking but fixing tiny things like that make up polish.
Other than that, it would be great if the game was a bit more fast paced, this is personal preference, someone else may prefer it as it is, so take it with a grain of salt.
Good job on the first game!