Some modern games use encrypted CPK files. You may need a specific "decrypter" tool or a "File ID" to unlock them.
: If you're working with CPK files in the context of Construct 3, a popular HTML5 game creation tool, the official Construct 3 documentation provides insights into working with projects and their file structures. download cpk file explorer link
To download a CPK file explorer, you can try the following methods: Some modern games use encrypted CPK files