GameBox
From Just Solve the File Format Problem
GameBox is the game engine used in all games developed by Nadeo, such as the TrackMania franchise. This engine relies on GBX files, which can hold any type of game data: settings, tracks, vehicle skins, sound effects, replays of past races, etc. What type of data is stored in a GBX file is determined by a class ID.
Software
See also the software listed on the Mania Tech Wiki.