Mechwarrior 4: Mercenaries is a battlemech piloting simulation and part of the Mechwarrior and Battletech universe unleashed by FASA Studios. In April 2010, MekTek received permission from Microsoft to release the game for free using their MekMatch torrenting program. Now that MekTek has refocused its energies on Heavy Gear, it is up to the community to keep the classic mech piloting tradition alive. This group will also serve as a platform for downloading new content created by the community, including new maps,mods and mech decals, some of which have been hosted by other enthusiast sites.
This is the official mission and map creator for FASA Studio's and Cyberlore's MechWarrior 4: Mercenaries.
It says I have to have Mech warrior 4 mercenaries installed to run the editor, but I do
Not sure if the MekTek build gives the proper registry entries that the editor needs.