When I still used DarkBasic (sorry 'bout that but I didn't know that Blitz3D existed! :)) I used negative light in my chess-like board game I was doing then (Archon rip-off)... My "evil wizard" had one negative light attached to him/her/it and it looked pretty cool when he/she/it moved across the board and "sucked" light out of the Neighborhood... looked VERY evil indeed! >:)