hello
I would like to create oldtype trees - you know, two perpendicular planars with tga texture applied. It is almost ok, but there is two problems too. First of all the planars collapses each other, in viewport and in realtime too. And the second problem is that hided with alpha areas looks ok when in bacground is standard blender background, but when I rotate camera and at first plane I have my alpha object and the second is any other object - the hided object covers the objects. I tried many patents, but nothing helped 
Please help.
best regards…raphael
we all have that problem, theres no way to fix this i think… at least, not yet…
sigh here I go again.
Translucent faces will overlap correctly if they are drawn from furthest to nearest. The current game engine does NOT sort them. Therefore things frequently overlap wrong.
the glaring solution is to add that feature to the game engine (difficult).
on some objects (unfortunately not your two-quad tree) the faces can be sorted prior to running your game such that they are always drawn in the proper order.
and I wrote a script to do just that (if it is possible)
http://www.geocities.com/z3r0_d/alphaSorting/index.html
(the link is now fixed on there too)