Well that's easy to predict. like this: say the map is this: XXXOOOSX XXXOOOXX XXXOOOOO OOOOOOOO OOOOOOOO where X = any tile, O = empty tile, S = special object (in this case a big asteroid) When DCME saves a map the space right and beneath S are being filled with O. If there are still tiles around the object continuum will draw in this way: XXXOOOO and then S. S is a bigger tile, but that doesn't matter, it just draws S on the map completely (like you would see it as just a big asteroid). Then a X is drawn, it just draws the tile as any other tile on its place, so drawing over the bitmap placed there of S. In the next row the last 2 X are also drawn over it. (that is if continuum draws from left to right, top to bottom. If continuum were to draw from right to left, bottom to top, the left top tile of a S is drawn last, so that would make the S the last drawn element, overlapping any other tiles that were already there.)