The game is free but there are stronger Weapons that are available but will require a few in-app purchases to unlock the range of Premium Weapons.
Quick Tip: Weapons that can go through zombies is best used for zombies where
1. Grenade Launcher
Description: Tap once to launch a grenade
Range: Extreme Long Range
2. Crossbow
Description: Tap once to fire. Retrieve fired bolts by running over a zombie that was just shot.
Slow rate of fire.
Range: Extreme Long Range
3. Cartel Twins
Description: Dual Wield Pistols
Range: Medium Range
4. TZR 44 Revolver
Description: Bullets can go through zombies
Range: Long Range
5.MFD-4 Assault Rifle
Description: Bullets will go through zombies
Range: Extreme Long Range
6. X4 Concrete Cutter
Description: Has more capacity for kills but requires more gas
Range: Close Range