I think you're spot on about the power of video games being in presenting questions, not answers, and letting the player explore the game's question as an agent (choice), rather than work through the author's statement (answer). Crime and Punishment tells us that there are no supermen and salvation is our only hope; Crime and Punishment: The Game would let us, as Raskolnikov, explore this problem ourselves. Of course, if the game has the same thesis as the novel, there's only one winning condition (spoiler alert: turn ourselves in), negating any agency in the game. Isn't this the trap BioShock fell into, exploring free will (ironically, by robbing the player of it but disguising it in a game-ism: "Would you kindly"), but failing to deliver on that exploration after the twist? In fact, most good-evil games seem to fall into a similar trap, as the developers favour the good path over the evil path, subtly (or not) rewarding the player more for the choosing the former.

Is a game like SimCity most like the non-persuasive, question-asking game? Of course, it has its own in-built political biases—public transportation is positive, high taxes are negative, etc. It also lacks winning conditions. Maybe I could have more to say when I finish Fable 2, which seems to offer the most grey-area non-dichotomous agency in a game thus far. Just had some thoughts to rattle off.