This can really be done indoor or outdoors. You need at least 15 people, but the more the better.
You will need to prepare beforehand a piece of paper for each of the youth. Write on each piece of paper:
1. A job occupation
2. A personality disposition (scheming, fastidious, mean, etc.)
3. If they are Christian or non-Christian (Important to give no more than 1/3 of the youth “Christian”)
Hand each youth a piece of paper and tell them not to show it to anyone else. The MC will say that the youth room, church building, outdoor field, or retreat center that you are at represents our city. They are all citizens of that city. They have each been given a job (or unemployment), a personality trait, and been told if they are Christian or not. For some time, they are going to live in this city. They are allowed to do whatever they want during that time. I also encourage them to think of a specific person that fits their characteristics (helps them to act like someone different) and imitate them.
Let them go to it and have the youth workers make sure no one is not participating or causing unnecessary trouble (maybe the workers can be the city police…). You’ll be amazed how creative the youth will be. After around 20-30 minutes, play a loud trumpet blast from a stereo or a real trumpet. Have everyone gather into the starting room. Separate the Christians on one side of the room and the non-Christians on the other side. Explain that Judgment Day has come. All of those who were Christians or who converted to Christianity are in Heaven. All of the rest are now in Hell.
Ask first the non-Christians why they didn’t become Christians. You will get a variety of answers. Probably some will say “No one ever told me about it,” or “How was I to know?” That is a good time then to turn to the Christians and ask them why the others are in Hell. Ask them very gently but directly if they tried to witness and why or why not.
You can end this part of the discussion explaining that we do not know the day or the hour, but one day there will be a separation of believers and unbelievers. At this point it is good to bring the two sides together and have an open discussion on what our responsibility is to persuading others to accept Jesus and how the youth can strengthen each other in doing so.