If the official update still prompts for a disc, community-made "Fixed EXEs" are available on sites like GameCopyWorld . You simply copy the new Doom3.exe into your installation folder, replacing the original. Modern Alternatives: Source Ports

PATCHING DOOM3.EXE... MEMORY OVERWRITE DETECTED. HELL PROTOCOL ACTIVE.

Instead, buy the modern version:

Leo’s dorm room smelled like burnt coffee and desperation. On his screen, a single error message glowed like a demonic rune: