Most modern repacks have a checkbox to "Limit installer to 2GB/3GB of RAM." Even if you have 16GB of RAM, check this box. It makes the installation slower but significantly more stable.

Three hours later, the 7z file sat on his desktop. He ran the setup.exe. The installer was beautiful in its ugliness—a crude Windows 95-style window with a progress bar and a single checkbox: “Limit RAM usage to 2GB (avoid crash).” He left it unchecked.

You will typically download several small .rar or .zip parts. All parts must be in the same folder before you begin extraction.

– Even if a repack appears to work, you won’t receive updates, online features (including online multiplayer and seasonal content), or technical support from the developers.

If you want a legal, highly compressed method: use or NTFS compression on your legit Steam folders to shrink the game without breaking it.