I'm new to this so it may already be a feature, but I think it'd be awesome to have mini-challenges within the game. These probably would not be able to be verified, but just little things that the original game creator could add. Things like "do 3-5 hours of low-level cardio this week." It may have to be an "on your honor" type thing, but maybe have a button for everyone to press that says they completed that week's mini-challenge
I have an invitation-only game, and I plan to do this on facebook just between the players. They would comment on the challenge post when they complete it. I think I will give a 2 day window to do the challenge in, as schedules vary. I'm even thinking of a point system with my group. If you complete a challenge, you get a point, if you send a picture of you doing the challenge you get 2 points. Whoever gets the most points in the end, wins a gift card, or something. I won't be able to win it, but the incentive is that it's MY game, so I'd better be a good example! Most entrants are Christian friends, so I think we can trust the 'honor system'. Great idea! Makes the game more fun and helps reach the goal faster!