More of attenuated and ambient lighting. The fifth pic shows four differently colored spotlights as well as different ambient light color for each cell. This gives the illusion of decaying light intensity on global scale. This way, lower number of omni/spot lights needed as ambient lights most cells. Ambient is dropped in later version when bumpmapping is introduced into the editor because the bumps look flat on ambiently only lit walls. Shadows are still not implemented in these pics. However, walls facing away from light are not lit with omni/spot lights but can be ambiently lit instead as the third pic shows a pipe facing away from light yet the pipe can be seen as gray.