Theme: Atmosphere
Main Idea: A level where you walk through rain with an umbrella
Secondary Ideas: Jumping over puddles, making the rain intensify and shift left on a speed up, thunder ruins the path and you have to do some good gameplay to get around it, at the end of the level you get home and it's all cozy.
Basic tradeoffs: Time, I can take as much time as I need if it makes the level better, i'm not being forced to do anything. Also I love optimizing my levels and making them better, even if it takes hours.