For me making a retro world is not sign of laziness. Why? Because you can't allways remake a level in 100% - some enemies items and other thing that are in one game, don't have to be in another and here's a point of creativy - make something to give you feeling of retro level but with new features.

Retro World won't be kind of world that you can easily acces. I mean this world and world 7 (Outer Space) would be bonus worlds. To reach them you'll have to find to canon hidden somewhere in 2 levels, that will take you to these world.

I updated first post so you can see how retro world will look like. There are still 4 levels to do, so i hope I'll finish it soon. Then I'll move to Grassland and try to redone it.

PS: Last thing about logo. Is it possible to remake it into 14 colours so I can use it in game?