http://www.puppenheim.org/trees_o.wdl

I think it is a version, that I didn't change too much.
The script has the drawback that it decreases the frame rate extremely when there is no tree near the player.

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