Most of the pnFlashGames folders are pretty self explanatory. Here are the default folders, an explanation, and the permissions that should be applied to each one.
/docs - Documentation pertaining to the pnFlashGames module
/games - Default location for all game files and thumbnails
If you are using the auto-install subscription service, or are using the "Import" feature to install games, this folder must be writeable by the web server.
/modules - Location of extensions for pnFlashGames
/pnblocks - Where all the PostNuke blocks must be located
/pnimages - Where all the images for pnFlashGames are located
/pnlang - Language files are all stored here in their respective subfolders