This is a screenshot of my tank game, created in DJGPP with Allegro 3.9.12 (WIP). (I don't
know whether or not you know about these but when you don't have a look at www.delorie.com/djgpp
and www.talula.demon.co.uk/allegro )
A short time ago I added a lighting system, which is based on a binary lighting tree for
each tile. I think I can't tell anything more about it here, so if you want to see the code,
try out the exe, please mail me. (you'll find a bit older version at www.mrdevlin.50megs.com )
I'll send you a better description of this nice tilemap lightingsystem.