Really cool concept, but time to kill is way too long for such a fast paced game. Landing one shot kill with headshot would be very satisfiing.
Also as UI designer I would suggest you to change the font to something more readable, but still modern/futuristic. This one might be good but for headers or big texts, but for the rest it would be better to use something simpler.
Movement should be smoother, I can feel some kind of delay when I release the button and the character is still moving, so e.g. pickup up the weapons is pretty difficult.
Your game have pretty similar feel to Severed Steel, you might want to check how the movement and balance feels in that game to inspire you.