Zombies Are Coming Xtreme

In this zombie survival game, you're thrust into a cityscape overrun by zombies. Man a stationary turret dead center in a zombie-infested city.
Your turret shoots bullets automatically. Swift and cunning zombies demand your attention. Quick sprinters and some evasive undead are relentless.
Your key to survival lies in upgrading your turret. Collect power-ups to enhance your firepower. Will you stand your ground, or will the relentless horde prove too much to handle?