While we're on the topic, here's another technique for quickly setting up Dynamic Lighting for Caves: Make the background black. Draw the dynamic lighting lines loosely around the outside, forming a cozy envelope. No need to be too careful here. Draw Cut in Lines (baffles) perpendicular to your envelope, into each corner. If the background is black, players shouldn't notice that the DL lines aren't precisely hugging the walls. See it with the black background at 9:04 At about 9:35 you can see where I missed one and had to fix it . (Note: If your premade map has a lot of secret doors, the envelope+cut-in technique might not work for you. If you're building your own map, secret passages can be offset with a gap. )