Decided to put out another quick update before focusing on ARENA mode. Here's the changelog:
*Faster bullet speed
*Thinner bullets
*Player health system
*Bloody screen when player is hurt
*Heavy breathing sound when player is hurt
*Enemy guards use predictive aim
These changes make the game much more immersive and the difficulty is both harder and easier at the same time with the new health system.
Here's a little GIF showing the changes! (the GIF is grainy due to having to optimize it's file size)