This has a neat concept, though my playthrough was very buggy.
The sounds are not well normalized. I was not able to find a good volume where I wasn't having some things feel too quiet and others too loud.
On the upgrade screen the Health boost shows it will replace the claw, though the text says it is a Boost Upgrade. Purchasing it did not replace the claw.
When fighting the turtle I tried charging in and clawing rapidly. After I died and the popup showed, the character was still attacking and defeated the turtle, including giving the victory dialog and then going to the upgrade screen. I bought a health upgrade, and then clicked retry level, and was on the next level.
I bought the health upgrade 3 times, but it seemed to keep being lost. Once was before the turtle level where I lost, so restarting the level may have reset it. Then after defeating the turtle I bought it again, only after the purchase noticing it had been reset. I was able to beat the bird level without restarting, but after it the health was again back down to 10. It is possible that the reset bug caused future issues.
When starting the ferret/weasel level I was shooting, even though I was not pressing a button. I got it to switch to the claw attack and was able to get close and hold left mouse to rapidly do the claw attack, while it was standing still launching grenades over my head, and only occasionally hitting me. After I defeated it, the claw attack continued and I was unable to move. The character still turned to face the mouse, but that was about all the control I had. I could see the materials, the enemy's helmet, and their grenade belts, floating on the screen. I pressed F12 to see if there were any errors in the console. That was the first I acknowledged that the claw attack changed direction based on where the mouse was. The animation was the same, except for the white curved lines, and I had not noticed before, but moving the mouse down to the log I was suddenly digging through the ground.