There is a engine Bug if you use TGAs with alphachanel in 2D games and have scolling backgrounds. You can set the second backgorund exact next (or behind if you use parralex scolling) to the first one but on some places the first one blends into the second one and if you use shadows on the background they sometimes are visible and sometimes not. It just happens if you use TGA with alpha chanel. I got the same problems with my Moon Patrol remake and fixed it with a material i got from the Wiki Page , just search under ImprovedOverlay but this dosent work here. We need to look for an other solution.

Hope my poor english makes it understandably for everyone