Black Ops 2 changes up the formula for the Call of Duty games by introducing alternate endings. Similar to games like Bioshock 2, there are several key events that need to happen in a certain way in order to get a particular ending.
The total number of endings in the game numbers to about 6 and this guide will instruct you on what steps to take in order to get the best one. Naturally, due to the nature of the guide, there are some pretty hefty spoilers up ahead, so read at your own risk.
While there are some smaller objectives that you need to complete peppered throughout the campaign, the big decisions that you need to make are as follows; save Mason, save Karma, and spare Menendez.
Here are the rest of the requirements for the best ending:
Rescue Woods in the Pyrrhic Victory mission
Recover the worm in the Celerium mission
Interrogate Kravchenko successfully in the Old Wounds mission
Find all the intel to know everything about the CIA mole in the Time and Fate mission
Protect Harper and find the intel about Zhao’s secret meeting in the Fallen Angel mission
Kill Defalco and save Karma in the Karma mission
Make sure Woods does not succumb to Menendez’s in the Suffer with Me mission
Make sure that the SDC allies with US military forces and keep Farid alive in Achilles’ Veil
There are a number of objectives in the Odysseus mission; Save Admiral Briggs, make sure that the SDC protects the USS Obama with Drones and that it survives long enough for the SDC reinforcements. Lastly, ensure that Karma & the ship survive the attack