Your attention to detail makes me really impressed. It's visible how much work you put into this and it pays off because for me this is definitely one of the most impressive smwhacks ever and I've been following this thread for some time now.
Your graphics are stunning! The colors, the style, everything blends so perfectly and give every one of these screenshots their own atmosphere. That parallax in the jungle levels is gorgeous, and your work with layer 3 is awesome. I usually say that the best way to do a layer 3 background is to make it not look like it's on layer 3.
I'm really loving that lava cave ambiance. The idea of using layer 2 for the lava pillars is really clever and that wavy hdma slowly fading as it goes up is the cherry on top.
Keep up the good work! I know how time management can be so much complicated, but i can't wait to see more of this project