I tried it several times, one of them, the water was perfect from any perspective above the water. The other times the waters mirroring consists of sort of rests of other 'views'.

Heaze and soft stencil doesn't work this time. Dof doesn't have any sharp focus.

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