Your goal in 'Into the Dead 2' is to reach the end of the level by using your weapons to defend yourself if anything gets too close. You will find that as you progress through the levels the zombies will become more resilient and you will require more powerful weapons to deal with them. This means seeking out the necessay weapon parts that can be found in loot crates scattered throughout the levels to either build them for the first time or to upgrade an existing one.
Into the Dead 2 features an evolving story that has multiple endings. There are 7 chapters that contain 60 levels of unique challenges where completing them will enable you to unlock and upgrade melee weapons, firearms, explosives, and more.
Remember, the more challenges you complete, the more Stars you earn, and the more stars you earn in a level, the better the items will be inside the loot crates you find.