the game is made with opengl..

i will repeat what i said; this is a simple game, made to be fun.

i will repeat the thing #2: the geometry in other games is read from file,
here all the info for one block is taken from a 3D grid and
each cube face has texture number, rotation, flip and transparent numbers.
and now i generate geometry for this thing at runtime, thats why my fillrate
is slow and would be even slower just because you want stairs to be
completely 3D..