Yes, the strategy for rollouts (the rest of the game after you leave the currently explored tree) are still an area of research. The successful programs usually

Yes, the strategy for rollouts (the rest of the game after you leave the currently explored tree) are still an area of research. The successful programs usually involve some sort of local shape matching or other heuristic, sometimes trained using ML techniques. One of the surprising results is that having stronger play between opponents in the rollout phase does not always equate with a successful search. Having a balanced strategy -- that is, one that does not introduce a bias for either player -- appears more important.