One sentence, two intentions.

You get a mission and the start of a sentence. On your turn, add one word before time runs out; complete the sentence together.
Keep your role secret. If you're innocent, keep the sentence on mission. If you're a saboteur, steer it toward your secret goal.
When writing ends, each word's author is revealed. Discuss, then vote for the person you suspect is a saboteur.
Then the secret goal is revealed: did the sentence go off mission? Decide together; roles and points are revealed afterwards.

Play in the same room or on a voice call. The highest score wins at the end of the game.