Instructions: Check.
Sprint: Check.
Mouse look: Better, but there's a new error. After playing for ten minutes, the range of rotation was limited to less than 90 degrees.
Zombie AI: As a quick fix to prevent zombie clumping, I would set them to navigate toward the player only within a range of 30% of the play area's diameter. If the player is not in range for a zombie, that zombie heads to the center of an assigned quadrant where it randomly roams within that quadrant. This would make the zombies harder to kite.