I'll assume you're a new designer, I'm glad to see new works.
I remember a level that is this theme, the theme of "multiple dimensions", and I recommend a level I liked, it's Wonder Terrace. Perhaps you will find some ideas there. It was in the January/February 2011 Contest.
My personal advices :
- The crystal blue, and anything else that has a different color to its dimension are not good. The crystal blue in the desert is inappropriate as cactus would not be suitable in a water cave ...
- In the green dimension, you should create large trees to improve the visual sector and also emphasize that this is the galaxy "nature". Be careful though as the trees do not block 80% of Sonic's way !
- While each dimension has different textures, we also provide them with different challenges. For example, you can place rocks falling into the orange dimension (Linedef type 12) ...
I need an information. How Sonic goes from one dimension to another ? With a teleporter ?
I will come from time to time to see the progress of your level.