Steam-repacks Info

Most repacked games cannot access official Steam servers for multiplayer unless they use specific "online fixes" that simulate a legitimate connection.

A repack is a retail game that has been heavily compressed using advanced algorithms. While the original game files are preserved, "optional" content—such as high-resolution textures, 4K videos, or additional language packs—is often separated into optional downloads to minimize the core file size. How They Work Steam-Repacks

Repackers use tools to shrink game data. For instance, a 100GB game might be compressed into a 30GB to 50GB installer. Most repacked games cannot access official Steam servers

PSA : How to install a repack on your SteamDeck running SteamOS "optional" content—such as high-resolution textures

Collectors use repacks to keep "complete editions" of games (including all DLCs) in a compact format for long-term storage.