Hi Evil-Dog and everyone involved in this game,
I've been studying sound design for a couple of years now and it's refreshing to see something experiment with audio to this full effect. I hope you continue to do so in your games as I think it's a very important part to games.
I did enjoy the concept of really listening for the voice to get your timing right. I just think there are a few things you could have done to make it a bit easier to play. Bear in mind my headphones aren't fabulous but I'm sure you want your audience to have a range of different quality headphones.
Firstly I think it was hard to know when you were moving. Because the players footsteps mixed in heavily with the enemies it was hard to distinguish between them. Perhaps a visual cue like a keyboard glowing when you pressed each button will help with that sort of thing.
I also think the non diegetic music was a big distraction trying to listen to the diegetic noise of the fight. To avoid it sounding empty you could some natural ambience of nightlife wildlife or the wind blowing etc; to still get the tone your going for.
However I think this was a very creative project and a great concept. Wish I could work on something like it some time!