You should read that paper I linked. Chance moves by Nature in:

http://en.wikipedia.org/wiki/Extensive-form_game

can be confounded with each other, and in fact often are (in the survivor effect example by the underlying health status). It is very easy to add confounding to anything, it is a fundamental issue you have to deal with. That was one of the points of my talk.

You need causal language to describe "the agent's situation" (where confounders are, etc.) properly.