Very impressive, love physics! :D
Some constructive feedback I can think of is that the spawning now feels very random, I died a few times by enemies just spawning on top of me and starting to shoot :P
Also I think it would be better if enemies spawn on one side and you on the other so it will be easier to play tactical and covering an area. Because of the random spawning (I think its random) now an enemy can just pop out of nowhere even though you think you have covered your back.
It feelt sometimes like I got shoot before I even saw the character. Maybe a more zoomed out view would have been nice, or even a minimap.
Overall though its an extremely welldone game! Love it :)