Highly compressed games use advanced algorithms (like or Huffman encoding ) to remove redundant data, often shrinking files by 30% to 50% for easier distribution.
Some "highly compressed" versions (often called rips ) may remove "unnecessary" files like multiplayer assets, foreign language audio, or even cutscenes to reach ultra-small sizes. System Requirements for Advanced Warfare
Regardless of the download size, the game still requires a specific hardware baseline to run effectively after it is fully decompressed on your hard drive. Call of Duty: Advanced Warfare Minimum System Requirements