For games that are no longer available for purchase, preservationists have turned to established archives to maintain the console's legacy: Xbox 360 Store and Xbox 360 Marketplace FAQ | Xbox Support

For the purest preservation, check your file against the database. Redump is a community dedicated to preserving disc images. If your file matches the checksum (MD5/SHA-1) found on their database, you have a perfect, unaltered copy of the game.

For consoles with or JTAG mods, users often seek "verified" game files (often called ISO or XEX files) to ensure they aren't corrupted or containing malware.

The game that defined two generations of consoles.

Hundreds of hours of gameplay in a single verified file. Gears of War 2: The peak of cover-based shooters.

View your Xbox Live download history on Xbox 360 | Xbox Support

Even with the store closure, you can still download games through official channels if you have previously purchased them or are looking for specific free titles:

Ventaja: Enlaces directos a MEGA o MediaFire. Seguridad: Siempre escanea los archivos .rar con VirusTotal antes de abrirlos.