Buy the game legally, then manually compress it using tools like CompactGUI (Windows 10/11). This uses native Windows compression (LZX algorithm) and can shrink the 45GB game to roughly 25GB without performance loss.
Call of Duty®: Modern Warfare® 2 Campaign Remastered - Battle.net
Thanks to scene groups like FitGirl, DODI, and ElAmigos, you can now find Call of Duty Modern Warfare 2 Remastered Highly Compressed New versions ranging from 12GB to 14GB for download.