Yup, that right about require game disc to run if game data is installed in HDD, it's just for improve the loading time, same goes to PS3, console use half installation, could be 5 GB or less but PC version is fully installation at 8 GB to 15 GB for most newer games.
For PC, that's different from console, some PC games require disc to run but can use patch to override the requirement of running game disc and great for laptop to save battery life without DVD/CD start running like spinning.
I found no CD/DVD patches from GameCopyWorld for PC version at often.
