I'm very interested in how you accomplish this. I'm planning something similar (as in Metroid meets JJ2) for Devil Dash, but in a much later episode, so by that time I'm surely not going to be all that innovative if you manage to make this as you imagine, but proved ground will be much easier for me to thread and I will be able to focus more on storyline and art direction. It's a bit of a selfish approach, but it's all for the good of JJ2.