Here's a cool idea I thought of for zombie mode. What if there were to be a workbench table thing which allowed players to buy attachments for their guns. They would go up to the table and press the action button and it would bring up a menu with a list of attachments and prices. They'll still be vulnerable, so it's best to use it at the end of the round or when there's a crawler. Useless attachments like silencers and infrared won't be available, as zombies don't have mini maps, and I'm assuming no body heat because they're dead. Maybe have powerful attachments, like grenade launchers be available after a certain amount of rounds. This wouldn't replace pack a punch, as it does not affect the weapon stats, just gives it attachments.