If NWN was an "Open" game, then I guess Pac-Man would qualify too. Your cheese avatar could choose to clear out the dots to the east, west, south or north first (picking up some phat loot along the way). In the end though, it didn't make any difference, you had to clear the entire gaming board. Only choice being which one of four you picked first. None of the four things you had to fetch in each act was optional (Ok, so I died from boredom before completing Act IV so it might have been different from Acts I-III, but at least I tried).