like mikey said, i would make a video to show you how to compress a game from start to finish.
you need to search files of the game for precompressability, then if they are indeed recompressable they go under deflate mask. if not they go in normal or if non compressable they go to void.
this think can be done by a video easily.
there are repackers out there that prefer to absolutely squeeze a game and take 3 hours 50 minutes to decompress.
i have made Dragon Age Inquisition unpack in 40 minutes using 4 threads vs a repacker on net did it in 4 hours almost..... learn to be efficient along the way, this is where masks kick in...