Still no correct normals. Tried whether the material could be the reason, but assigning a new material to all models didn't chenge the difference of the shading between the original models and the merged model.

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