PROBLEM
Ok first of all, good game, I do actually think it's a good concept you got here, BUT, there are problems with the game...
The levels are too repetitive, there are two appearances for the zombies and now difference in attributes, and the only added difficulty is extra zombies.
Which brings me to my next problem, using the mouse movement as the I found that the only real way to keep going without being hugged to death by the zombies is to run into a pack of them with your leg flailing, stay near the window till you stamina refills and have another go. A single zombie or small group is a fantastic thing to knock around but in the end there is just no such thing.
Also, what's the deal with the grabbing? the only way to stop them from grabbing you is to keep your distance but that isn't happening because guess what? Mr. Headphones there is gonna PUNCH THE CRAP OUTTA THEM XD XD XD
But now I look like an ass, but I really think with a little work, a different combat system, some more enemies and mabye even powerups you could make a fantastic sequel.