Omega makes the prediction by looking at your state before setting the boxes. Let us call P the property of your state that is critical for his decision. It may be the whole microscopic state of your brain and environment, or it might be some higher-level property like "firm belief that one-boxing is the correct choice". In any case, there must be such a P, and it is from P that the causal arrow to the money in the box goes, not from your decision. Both your decision and the money in the box are correlated with P. Likewise, in my version of the smoking problem both your decision to smoke and cancer are correlated with the genetic lesion. So I think my version of the problem is isomorphic to Newcomb.