There had been already a complete tutorial of that including demolevels. Perhaps, it is at Achnex Resources? - Nope, looked for it. But, there are two others!

Better set search range to "older than".

Even in AUM could be one.

http://www.puppenheim.org/
http://www.wuerfels-welt.de
Old Game Tutorial: http://www.puppenheim.org/MITutorial.zip
Free Game Editor: http://puppenheim.org/AlienalsWeihnachtsmann.zip
http://www.puppenheim.org/blender_starting_main_settings.txt