Hi Christopho,
For the walls and floors, I though it was ok but I agree that the holes need graphic redraw. I am not a very talented graphic designer plus I am colorblind which does not help much.
For the moving plateform, I used a dynamic tile and a custom entity. I just have an issue to finish, reset the positions and logic every time you past a separator or else you get what you see at the end of the video, desync platforms. When I have cleaned the code, I will release it on the forum.
The conveyors are also a custom entity because the one hard coded pulls you into the middle which I did not like.
The same goes for all the enemies you saw (except bubble). I have to change the graphics yet again.