Call+of+duty+modern+warfare+2+highly+compressed+40+mb+for+pc+full

I need to check if there are any official demos or mods that are compressed. For example, some games offer demo versions, but for Modern Warfare 2, the full size is probably not compressible to 40 MB without issues. If they are talking about a mod, there are community mods, but again, 40 MB is extremely small for a full game.