it's possible with events but extremely annoying and hard to make.
here is what you need to do:
step 1- make the cave
step 2- cover it with events - 1 tile = 1 event.
step 3 enable walking on a dark tile of your choice
step 4 don't touch the first page of any event, make a new one precondition it with a switch (EVERY TILE MUST HAVE A DIFFRENT SWITCH BUT DO NOT USE LOCAL SWITCHES)
step 5. change the graphic of it to the black tile you can walk on
step 6. choose "dark and light" spots, cover rows with hero touch tinting so that there will be a tinting affect causing tiles to look darker even when seen.
step 6 and the most annoying one, remember those first pages you elft empty? all of them must be set to hero touch and xcluding the tinting some of them do all of them have to switch on and off the tiles around them
so say you condition x1 x2 x3 etc and the map looks like:
(X= tile n=number of tile, for example X1 X2 X2923)
XnXnXnXnXn
XnXnXnXnXn
XnXnXnXnXn
XnXnXnXnXn
XnXnXnXnXn
now if you are in the middle a move to the left will trigger hero touch of Xn+1x (1 x tile) in it you will switch off all the tiles behind one row before it and switch on all those who are one row infront of it (xo=on Xf=off Xm=middle after moving)
XfXfxfxfxfxfxf
xfXfxoxoxoxf
xfXfxoxmxoxf
xfXfxoxoxoxf
xfXfxfxfxfxfxf
this will create a square of 3x3 of light if done right, the graphic of those events should be left empty so that the map will be showen
it's insanly hard work and i think you are going to use like 500switches on it but i can't think of a better way atm xcluidng maybe a script