Neat idea and a fun execution on the theme :) I really liked the raycasted shadows and the general level of polish everything seemed to have!
I'm kind of curious how the game would feel if the zombies chased you when your torch was out and they had line of sight. I noticed I mostly just avoided zombies or spam fired my gun when going around the map. So perhaps adding some pressure might help force the player to make more delicate decisions of what to do.
Very cool idea though, y'all did a great job! I love seeing team games and hope you all keep together making games :)