Played all the levels. Video:
I like parrying a lot! I feel it added to the gameplay, though I felt I was spamming keystrokes like crazy, a ton of jumping and turning to aim. I still have difficulties wall jumping while gaining speed, since the place where the mouse is needed changes depending on the position of the character on the screen. I held both mouse keys at the same time for the chainsaw, maybe for easy to use, it should always stay enabled when shooting normally.
The menus backgrounds are awesome.
Keep up the good work!