For Shadow Play, I'll do what I did with Cloak of Shadows, which is pretty much the same thing you just stated - without all the model work. I can apply an all black shell around the caster as a temporary effect without changing the model. I'll just change the rules a bit by allowing you to move around, but trigger the effect to end when you transition levels.
I'll hold off on Black Metamorphosis till you make the model.
I've got Vicissitude ready to develop as well. I just need some Flesh and Bone craft variation models for each of the skeleton types. Oh yeah - and a horrid form for each of the skeletons too would be nice. I've added quite a bit on my plate. I've decided to take on the following disciplines:
Chimerstry
Dementation - I'll even add a section for easy construction of derangements, including a new derangement command.
Dominate
Necromancy - Only the Selpulchre Path and the Bone Path will be developed. Not messing with the Ash Path.
Obtenebration
Quietus
Serpentis
Vicissitude
I already wrote up all of psuedo for the above powers so it should be fairly simple to create the code. I know that Obtenebration and Vicissitude will be the two most difficult ones because they demand some new models and involve non-conventional shapeshifting. Without the proper models, there's no point in developing those two. All the other disciplines that need custom effects usually involve making new particles or basic templates - nothing fancy or hard.