Ahhh THAT game. I remember checking that out when I was getting back into Construct after months of not touching it. Nice game! It'll be sweet seeing this actually applied in your game.
Just checked out the new LOS version. Very nice and accurate.. even at the slightest gap but it's around half the speed of your previous version. So it's gone from 1200fps from the previous version to 600-800fps for this version here. That probably doesn't make any difference, as long as it runs smoothly on a lower end machine. If it's accuracy you want, then sometimes you have to sacrifice a little speed I'm curious how it'll perform on so many swarm cells though.
I wasn't around yesterday (well only in the morning and that was brief) so didn't get anything done at all... but had a few thoughts. Based on your intitial LOS system, I thought of a way to optimise a bit.. I think by checking the angle from the lightsource to the obstructions (circles) and the angle of the player object, we can check if the player's angle is within a certain range close to the obstruction's so we only need to cast rays from that obstruction's edges. Don't know if that makes sense, as it's just in my head atm so hard to explain. I'll see if that works...