So at the end of day 1 we have actually made some good progress. We have a level editor where you can place platforms/doors and keys of different colours and the collisions are working with the good colour matching (so far), so if the character is yellow he does go through a yellow door as planned:

In addition to this we have about 8 levels designed (couple of examples below):

We also have the character drawn in various colours:

Good night!