There is only one file type that uses the .LVLX extension:
Extendable Level File
Level file format used by Platform Game Engine (PGE) Project, an open source game engine; stores one or more level locations, which may include level sections, player start points, NPCs, and doors available on the map.
NOTE: The PGE Engine has not yet been released but you can edit LVLX files with the PGE Editor.
|Wohlstand PGE Editor||Free|
Updated: July 19, 2015