maybe in easy free play maps everything stays the same shiny sky green grass. once you get in normal map the sky gets darker and dead soldiers everywhere, grass starts to die off. maybe for some map random stuff fall off the ceilling. then into hard mode. could be dark sky even lightning storm with torches everywhere and cracks in the roads plus dead soldiers and all the green grass turns black. (glowing eye rats everywhere) i only played a little DD1 and my english is not good. but this would be my suggestion to make same old maps a little refreshing, knowing you made it from easy to hard mode.