Here's a little exercise I used yesterday, an amalgam of several other games. The bigger the group the better it works:
1. Invite people, alone and quietly, to think of one favourite food they would order if going out for a one course meal.
2. Invite them to think of a couple more things (second favourite, third favourite).
3. Tell people that the aim of the game is for the whole party to go out for a meal and order the same thing. Do not repeat this, ever. Now invite them to find a partner. The two of you have to go out for a meal and order the same thing. What will you order?
4. Twos get into fours and agree.
5. Fours get into eights.
6. Continue for as long as it is fun.
When it becomes obvious that the room has polarised into non-negotiating groups, sit everyone back again, especially the group of sixteen who, with their backs to the wall, are shouting lasagna at the rest of the room in a football chant (yesterday's experience). Take a calming moment or two, then the best bit of this is the debrief. Questions to discuss:
A) At one point did you stop looking for compromise and become intransigent?
B) How can an organisation pursue its vision unless everyone buys in?
C) How do you avoid a 'lowest common denominator' vision where you all go out for gluten-free, non-dairy cheese sandwiches or suchlike?
D) Who can remember the aim of the game?
Feel free to select and adapt as you wish. If any user finds a room that can come to agreement treat them like gold and praise them as such