Black Ops 2 is an older game (2012). When it tries to write a small temporary file related to Steam’s API, modern Windows security features (especially when the game is installed on your C:\Program Files (x86) drive) that creation.

Or, worse, a tiny, smug error dialog box pops up that reads:

In the lexicon of PC gaming troubleshooting, .dll (Dynamic Link Library) errors are often dismissed as generic glitches. However, the steam-api.dll file serves a specific, critical function: it is the bridge between the game executable ( t6mp.exe or t6sp.exe ) and the Steam client. Without this file, the game cannot verify ownership, access Steam achievements, or initialize the overlay.

Here is how to check: