A very fun concept!
With a little more time in the oven, this could prove to be a fun experience. It would need some optimization: The game seems to stutter on occasion, and I fear not a lot of occlusion or LOD has been implemented.
Also, the balancing seems a bit off: A guard can basically 2-3 shot you if he is not stunned, meaning if more than 1 guard approaches, you're likely to die.