The most common method involves downloading a "No-CD" iw3sp.exe and placing it in the main installation directory.
The internet hummed with the static of 56k modems and early DSL. When the download finished, the ritual began: The Backup: Copying the original to a folder titled "DON'T DELETE."
New players often find that the single-player executable fails to launch even with a legitimate copy. If your "new" installation is crashing, try these proven fixes: