We usually just tell our groups to come up with the most crazy, off-the-wall, completely impossible ideas possible. Come back together as a team, present as a group to the team, and break up again. We do this a couple times.
The first hour or so in our divided groups is usually just a "what do we need to do" and "how is the gameplay going to look like?"
The second meeting is where the specific, impossible ideas come from.
We usually see some trending themes throughout our groups.
We always say it's better to tone down a crazy impossible idea than to build up a bad one
