I like the paiting, even though its just a prototype. N people hav been rating low cuz they think its subject isnt clear... of course it isnt, its a prototype, people!
Anyway, I think that the blank space on top doesnt fit with the penis. it makes it too bright n the top part is almost indistinguishable from the background.
The skull bothers me a little too. Its shape is right, but it could hav som more details, like the depth of the ocular cavity n it is a bit flat, as if it was smooth. N I presume that smoothness isnt the point of the paiting, is it? I'd add som scars. But thats only my opinion.
Overall, its a good paiting. Lookin forward to the complete project. Keep it up ;D