I played up until round 12 in the web version, where the one-hit enemies suddenly doubled in health which caused me to instantly lose since I wasn't prepared for that. I liked the progression, the enemy AI was really fun and evasive which gave it a good amount of challenge for me. The one problem I had that I couldn't tell if it was intentional or not was the sensitivity of the mouse movements were really sharp, whenever I moved a tiny bit it would completely throw off my aim, and that's where most of the difficulty came from for me. Overall, I really enjoyed it! A few suggestions would be maybe add an aim line where you're currently aiming so you don't have to miss first or look back to know where you're pointing, lessen the mouse sensitivity in some way (it might be tied to framerate if you didn't have this issue), and make the difficulty scaling more progressive instead of all at once.