Most files labeled "Call of Duty Black Ops 2 PPSSPP zip" are actually . Developers in the homebrew community take the base game code of Roads to Victory and apply custom patches to simulate the Black Ops experience on mobile and handheld devices.
Sites like isoroms.com often require "Human Verification" by forcing users to download unrelated apps or complete surveys before revealing a link.
You may see files listed as "highly compressed" (e.g., 100MB to 500MB). While the original console version of Black Ops 2 requires roughly 16 GB , these PSP mods are much smaller because they use the assets of the original 2007 PSP game.