GTA: Zombie Cops of London
The world is in chaos as the gangs appearing from out of nowhere and would always kill the cops. The government got mad and ask you to help the cops to immortalize the cops, so you conducted some experiments on them. But, the experiment wasn't successful as it turned them into zombies. When you learn of this, you felt guilty and want to do something about it. The idea here is to eliminate the zombies. You need to explore the area to find the zombies. Kill them as you see them. Collect the vile up in the air. Use your booster to get to where you should go.