Kill zombies before they detect the survivors s the main goal in the game. However, keep in mind headshots brings additional bonus.
There are 4 types of weapons the sniper rifles, assault rifles, machine guns and shotguns. Each type has it's own purpose during the course of the game. Upgrading them is a huge part of your game progress.
Use medals or gold to purchase supply drops. There are 2 options: the premium supply drop and the medal supply drop. The premium one contains a rare chest and alpha vest and it costs 50 gold. The medal supply contains a common lower body and a basic pants.