As is the case with all other Call of Duty
is multiplayer-focused. I'm not familiar with how these packages were weighted in terms of competitive vs. cooperative content in the past, but it's pretty even in this release.
Onslaught features four new competitive maps, or three if you recognize one of them as a remake. These maps are fun to play on, and each has its own particular environmental gimmicks and Field Order Rewards.
BayView appears to be a boardwalk. On this boardwalk are stores, cafes, and a special trolley service. Soldiers who are in a hurry can take shortcuts through the buildings, though many of them are equipped with metal detectors that are more than capable of giving you away. The trolley can also be boarded and used as cover, but there's a tradeoff; you're a sitting duck to everyone on the other side of the rail. If you complete your Field Orders, you are granted an artillery strike from a Destroyer floating off the coast.
Containment is a Mexican shanty town with vehicles littering the road and a giant ditch bisecting two key areas of play. In the center of the ditch is a truck containing a leaking nuke that for some reason causes greater harm to your minimap than to your body. The Field Order Reward is a mortar strike... that targets the truck itself. Enjoy.
Ignition is a retooled version of Modern Warfare 2's Scrapyard, a fan-favorite that happens to be a rocket testing facility. When you're not weaving through the train graveyard on the hunt for the enemy, players on the run can set off a memorable trap; by going to a test console and interacting with it, they can have nearby rockets test fire, incinerating everything in their paths. A larger test chamber is available to use as part of a Field Order Reward. Additionally, a large rocket automatically launches after a set time of play. The rocket's launch is a resounding failure, and the fuselage crashes back down to the earth. Unattentive players (like myself) will find themselves struggling with the world's most impossible bench press exercise in history.
I've saved the best (and strangest) for last: Fog. This sendup of old horror films is a bizarre place to put otherwise standard Call of Duty action. There's darkness, bats, waterfalls, and references. Oh, the references. They are everywhere if you know where to look (and if you are sufficiently..."cultured...") The Field Order Reward transforms you into Michael Myers from Halloween. The theme music plays and you pretty much feel unstoppable. It'd have been better if you could have played as Ash from Evil Dead, since that movie is referenced more emphatically in the map.