My heart was a jackhammer. I navigated to the bin/ folder. Inside was a modified executable: iw4sp_2a_patched.exe . Beside it was a text file, 2a_notes.txt , which contained the sacred, absurd litany of what "2a" actually meant:
If you only have setup-2a.bin and rar 1 , you are missing the first disk or part. You must redownload all parts from your original source. i setup 2a bin call of duty modern warfare 2 rar 1 patched