What a great game, from the music to the graphics. You get so focused on making it thru, just to find yourself with a greater challenge. The feature where you can build your own course is just plain awesome.
I played it more than a year back, before it had coins implemented. The version played I only got passed the first 6 levels (maybe it was 5...not so sure).
A linear game in RAD, it will definitely be something new. If you can manage to get the camera perfectly horizontal(this way you can use 3d objects and it will still look 2D) and follow the object. The other method would be to use 2D meshes and aline them perfectly and just use forces. It will all be the same, but I would choose the 3D option (but still actually 2D).
Do you have some other ideas as to how this can be achieved in RAD
I like it, not to hard to get the logic of the game working. The art and little features would be the hard and time consuming part. Also you have all those different blocks, but it is something to think about once the logic is set out.