.WLDX File Extension
What is a WLDX file?
World map file created by Platform Game Engine (PGE) Project, an open source game engine; contains the overhead map of a world; includes paths to different playable levels, which are specified in .LVLX and .LVL files.
Along with paths, WLDX files can also contain tiles, scenery, music boxes, and level entrances present on the map.
NOTE: The PGE Engine has not yet been released but you can edit WLDX files with the PGE Editor.