There is only one file type that uses the .XGP extension:
Xfire Game Patcher File
File created by XGP (Xfire Game Patcher), a program used for modifying the xfire_games.ini file used by Xfire; saves a list of XGP-managed games profiles, which can be used to patch the Xfire .INI file.
NOTE: The XGP software and XGP file type are now deprecated. XGP has been replaced by a newer product called Xfire Profile Patcher.
Updated: December 27, 2011