For digital backups of games you own, several community-vetted repositories host both NoPayStation
Without a RAP file, the PKG will install, but the game will say "This content requires a license" or "Copyright Protection Information is invalid."
Have a specific error code not listed? Drop a comment below (or ask your local homebrew forum). The scene survives because veteran users help new ones understand the dance between PKG and RAP.
Here is where the "crack" comes in. RAP files are licenses. When you buy a game from the PlayStation Store, the PS3 downloads a RAP file (or an encrypted RIF file) that proves you own the license.