You must unlock the Tier 4 map, "Riot". To do so, you must unlock each tier in succession. Tier 1 is available by default, and you must complete 50 rounds in any combination in those maps to unlock Tier 2. To unlock Tier 3, complete 75 rounds in the Tier 2 maps. To unlock Tier 4, complete 100 rounds in the Tier 3 maps. Tier 4 only has one map; "Riot". Complete round 10 in Riot and a DNA Bomb will drop. It will infect your enemies and turn them into zombies for round 11. Complete round 11 to view a cinematic that shows a large number of zombies overrunning the area.
Note: All Exo-Abilities require battery energy, which cannot be recharged. You can use perks such as Overcharge or Fast Hands to get better battery life and activate Exo-Abilities faster.
Note: Certain Exo actions such as Boost Jump, Dodge, and Dash will briefly make you appear on an enemy's mini-map. To avoid this, use the Blast Suppressor Perk.
Upgrade points used to improve your Exoskeleton are earned through completing the four challenges (Kills, Grenade Kills, Head-shots, Intel Collected) in the single player campaign. There are eleven upgrades for Mitchell which require a total of 33 upgrade points.
Perks are divided into three categories.
Certain maps have unique scorestreaks that are obtained from Orbital Care Packages.
Each class of weapon has one that is best in mobility, range, fire rate, accuracy, damage, and handling, as indicated below.