Hi, just a quick question.
In the blender GE say I have a level, and I wanted to had a building that u can enter seamlessly if i tried to place a cube for the house and delete one face, it messes with the other faces and truns them invisible from many angles and they are all invisible if you walk into the cube. Hope I explained this right. :yes:
Thanks 
Enabled double sided? Just a thought
Yea, what bull-frog said. Its almost certaintly a normals problem - all faces in Blender have 1 side. If you look at the wrong side in the Game Engine, the entire face is completely transparent. Either turn double-sided on, flip the normals (if you only need to see one side), or make the walls 3D (meaning they have depth).
How do you turn on double side? And thanks for replying so quickly
How do you turn on double side
select you object,
press F
press A untill you have all faces selected,
then W, select “set doublesided”
have fun