Hi there all,
I was recently making my trap door game and it uses an image mask to decide where you can and can't go like this:

I then have colour detector code decide if you are allowed to move in a requested direction ( yellow is where you can stand, black is not)
fortunately this thread here --> https://forum.thegamecreators.com/thread/226049 had better colour detection code than mine so I use that now.
It struck me that I could use this for all manner of things and the first example I've tried was a platform game.
It was just a distraction and something I wondered about so its not complete or perfect in any way, but here is an example of what you could do. It also uses the AppGameKit studio Scene creator, so you can get an idea of how (not) to use that too
It is commented as much as possible so that it might be of some value.
The art is my usual attempt to re-create the original stuff as i am no artist. although, I have made all the platforms white by default, so you can change their colour in your code to whatever you please.
to highlight this I have made them forest green. In the original ZX spectrum version the platforms were r:0 G:189 b:0 if you want to get the classic look