How to put images on a map so that they disapear when another image passes over them

Question

We are working to create a pacman type of game and we cannot figure out for to get colored dots on the maze to represent the food the pacman eats. Here is our code so far:

style = {Background -> GrayLevel[0], 
   BaseStyle -> {Directive[White, EdgeForm[], Opacity[1]]}, 
   VertexShapeFunction -> (Rectangle[#1 + .16, #1 - .16] &), 
   EdgeShapeFunction -> (Rectangle[#1[[1]] + .16, #1[[2]] - .16] &)};
embedding = GraphEmbedding[GridGraph[{20, 30}]]; 
g = GridGraph[{20, 30}, EdgeWeight -> RandomReal[10, 1150]];
tree = FindSpanningTree[{g, 1}]; 
maze = Binarize[Image[Rasterize[Graph[tree, VertexCoordinates->embedding, style], 
       RasterSize -> 1000], ImageSize -> 1000]];
m = 5;
DynamicModule[{diskPosition = {250, 450}, diskRadius = 15, pacman = {9, 4}}, 
 EventHandler[
  Show[maze, Graphics[Dynamic[{Yellow, Disk[diskPosition, diskRadius, pacman]}],
     PlotRange -> {{0, 200}, {0, 300}}]], 
{"RightArrowKeyDown" :> 
    If[PixelValue[maze, {diskPosition[[1]] + m, diskPosition[[2]]}] == 1, 
                  pacman = {1, 6}; diskPosition[[1]] += m],
 "LeftArrowKeyDown" :> 
    If[PixelValue[maze, {diskPosition[[1]] - m, diskPosition[[2]]}] == 1, 
                  pacman = {9, 4}; diskPosition[[1]] += -m],
 "UpArrowKeyDown" :> 
    If[PixelValue[maze, {diskPosition[[1]], diskPosition[[2]] + m}] == 1, 
                  pacman = {2, 7}; diskPosition[[2]] += m],
 "DownArrowKeyDown" :> 
    If[PixelValue[maze, {diskPosition[[1]], diskPosition[[2]] - m}] == 1, 
                  pacman = {-2, -7}; diskPosition[[2]] += -m]}]]

This gives us a pacman that moves along the white part of the maze. Now we want to be able to put dots along the white that disappear when the pacman passes over them.

Code taken from another question: program a wall in which an object can not pass