What you need
The game can be played with any number of participants. As science shows that discussions in groups larger than four tend to split, aim for 2-4 participants. It is possible to run two groups in parallel so if there is 6 or more participants split them into two groups if space allows for it.
You will need a table or a flat surface that everyone in the group can stand around. One deck of cards per group is needed. The game can be enhanced by having a large paper first placed on the table that the participants can draw arrows on.
If you are running two parallel groups, try to get an even representation of skill sets and backgrounds in them. I.e. don’t put all developers in one group or all people from one municipality in one group.
Explain the rules and goals, with those cards as a guide. Then either pick a scenario randomly for each group or just select them. Do the same for starting states. Have someone in each group read the scenario for the group and let them also have it for reference during the game. Give them all the actor cards that they need and ask them to place it on the table with the starting state as a guide. Then handout the first object cards with the instruction to place them on the table as well and talk about where that should be.
If it looks like they are on the wrong track, intervene before they deviate too far. Also ask them questions to make things that might be ambiguous to the group explicit. Try to engage the entire group, sometimes the quiet persons have opinions that can spark discussion in the wider group.
When it seems like a group has all the cards in place and agreed on the relationships between them, either pick a calamity randomly for each group or just select. Have someone in the group read it for the group and let them also have it for reference during the game. Continue facilitating, and when they are done with the first calamity repeat with a second one.
When they are done, ask them to reflect within the group on how it went. Is there anything particular that stood out to them while doing this? Any realization that they made? What advice would they want to give to a public body starting their work with open source?