yep thanks gb I forgot about sealing the map. In unity and UDK it's maybe easier because you can just create modular pieces, create prefabs (half staircase for example, that includes 10 modular pieces) DIRECTLY in editor and use them to compose the level. But the beauty of Blender pipeline is that you can create exceptional levels with a technology that is 20 years old!
[LITTLEOFFTOPIC]@gb: what abou SJ? did you find the engine you're going to use for the game? Such a pity you dropped FTE[/LITTLEOFFTOPIC]