Gosh, a 2.5D isometric platformer. You really dont pick the most easy thing to do. As you know, this is a 2D engine.
I made a example once, a year ago. It is not using projection. You might be better off looking at the tutorials for 'isometric projection' first. But here goes :
Working isometric platform model.
https://drive.google.com/open?id=0B1SSu ... mtWVnc1cDg
Using R0J0hound 's behavior.
I am PRETTY suprised with how nice this behavior does the Z sort & handles the Z-moving.
The layout is in layers, to easely build a level. On runtime it corrects for the layer offsets and brings all objects to 1 layer. Another awwsome plus for this behavior.