Thanks for the starting points so far. More details:
Our platform organizes group activities from a crowdsourced catalogue -- think Doodle for the whole experience, from picking the date and time to getting volunteers for tasks needed for the activity to happen.
We're thinking of a competition along these lines:
1. Invite advocates for charities to create an activity associated with their charity of choice. (In reality, most of these will likely come through personal invitation. We're well-connected in the charitable space so should have no trouble getting a bunch of entries.)
2. The winner of the competition is the group that gets the greatest number of people to do their activity (as measured by our platform).
3. The winning charity will receive a prize package possibly including a donation and creation of a video telling their story.
I'm well aware this is half-baked at this point and there are many areas of risk that need to be addressed. This is why we're looking to hire someone with experience, similar to how an event planner would work with a launch event.