The objective of the game is to survive each round of invading zombies after which a more difficult round begins. The player begins the game with a Colt 1911 and has access to a melee attack via a combat knife, as well as a maximum of 4 hand grenades.
Keep running around in circles as the zombies follow you, turn around to get some kills, and keep running. Repeat this process to stay as safe as possible, while being aware of your points (aka Essence). Ideally, you should open up the map as much as possible by opening doors and unblocking pathways.
Call of Duty Warzone is a free to play game. It's not on GamePass and it doesn't need Xbox Live Gold either. MW2 and its multiplayer component is not free. You need to buy it if you want to play the single player game or MW2 multiplayer.