You can now unlock an upgraded bullet for the machine gun, tommy gun, and shotgun. Unlock these from your Unlock Ability menu in the Main Menu.
- The machine gun can be upgraded to have explosive bullets that have up to 20% chance of exploding.
- Tommy gun can be upgraded to have stun bullets that have up to 10% chance of immobilising a zombie for 5 seconds.
- Shotgun can be upgraded to have poison bullets that have up to 10% chance of reducing 20% of a zombies health every second over 5 seconds (super against bosses).
When a zombie is stunned or poisoned you'll see the stunned or poisoned symbol on them.
With these changes I think you'll find that guns no longer feel like they are weaker than the bazooka and grenade launcher and now have their own unique aspect in helping you demolish the zombie horde.
Good luck Choo Choo Engineers, especially on Hard Mode!