So, your NaNo project is a handbook for a game. (NaNo Rebel! )

Everything still applies, but you have to twist it.

The "What if...?" question could be as simple as "What if Tolkien's world was playable by regular people?" (The What If for D&D.)

Protagonists could be player characters.
Antagonists can be NPCs, or end-bosses.

Now, I obviously don't know if this is a video, RPG, LARP, board, etc game, so the way the characters and participants in the game will be the answer to these questions.

You know your game, so you will know where these things can be applied.

Hope that makes sense.