I came here right after my Duolingo lesson :D
This game is pretty fun and I like the idea a lot.
I would improve the controls. It looks like the speed in X and Y axis are independent, which results in approx. 1.4 times higher maximum diagonal speed. (Nothing that couldn't be solved through the power of the goniometry 🤓)
Also, why not map attacks on the left and right buttons on the mouse?
But the art was lovely! Though the walls were a little bit too similar to the floor, as a fellow Duolingo hostage I approve! :D