Experimented some concepts and I think I've got a grasp of what I will be doing.

The level will be covered by colored foam mats. Standing on it will bring toys of corresponding color alive.
[media][/media]
Although the video is bullet-hell-ish, the actual game will take a more puzzling oriented approach.

The engine I will be using is Yatagarasu, custom made engine for another game I am developing: Mikobuster. The game will be mostly coded in Lua, and I will try to avoid modifying the engine side c++ code as much as I can to put the engine flexibility to test.

Next step would be creating art assets that will match the theme better.