Repackers achieve this by removing unnecessary localizations (language files), compressing audio to lower bitrates, and using "lossless" compression for textures. Legitimate repacks do not remove core gameplay.
To achieve high compression ratios, some repackers delete "non-essential" files. In a game like Battlefield 1942 , this often results in missing radio commands, music, or sound effects. The atmosphere of the game relies heavily on its sound design; playing without it ruins the experience. Battlefield 1942 Pc game Highly Compressed