Does someone has any experience in 3DFX / OpenGL
programming in Delphi?

check out http://www.sdf.se/~pm/delphi/
download tutor05.zip

then download prebuilt mesa(sort of GL - fully compatable) voodoo dlls
from http://www-hmw.caribel.pisa.it/fxmesa/index.shtml

and have fun playing.

Obviously only works with full screen.

I can send you some demo code (flying over a landscape) if you want.

..Steve