The game is a digital-only title available via the PlayStation Store. If you have previously purchased it, you can reinstall it through your on the PS3: Navigate to PlayStation Network on the XMB. Select Account Management > Transaction Management .
If you still want to proceed with downloading and installing a Castle Crashers PS3 ROM, here are the general steps: castle crashers ps3 rom download install
Word count: ~1,900+ words. For further assistance, visit the RPCS3 Quickstart guide or PS3 Homebrew communities like PSX-Place or GBAtemp. The game is a digital-only title available via