Game discs in folder PS3_GAME/INSDIR Can be considered an expansion of the basic blu-ray disc game structure, activated by default with the "g" HYBRID_FLAG from PS3_DISC.SFB
The presence of INSDIR forces a mandatory installation (warning screen with "Yes" or "No", if selecting "No" the game doesnt boots) performed in main XMB (before starting the game). When the installation is completed the game boots
Used for "game patches" and "game expansion packs". The PARAM.SFO inside "INSDIR" contains the "APP_VER" of the bigger patch of the folder. Note that "download content" packages doesnt contains "APP_VER" so its installation doesnt updates the main game. For this reason "APP_VER" is only related with patches. Other types of PKG can be installed but the main game will reload the message above because it was expecting to have a game patch.