Light leaking through walls

[TheGreatCthulhu]

Yeah - make sure spherical lights don't cross to the other room; rearrange them and/or increase their number slightly if the first room ends up being too dark. You can also try using a box light to control the overall illumination level and light tone of the first room, if it's possible to place it in a way that doesn't affect the other room. Also, you can create some ambient light effects by moving a large spherical light up (even above the ceiling), so that it affects a smaller area, with relatively smooth illumination, or use smaller, similarly colored, but a lot darker lights as fill lights for corners and such.

Alternatively, I think you could (at least in theory) turn on shadow casting for the lights close to the wall near the dark room, but it is possible that this could have some performance penalty, so try to avoid that approach.