Take a delimited area that could be the size of an elevator (a big carpet, for example). One side is the elevator door. You can play with elevator music.
The game starts at ground level.
Each player must shortly describe their character. Name, occupation, appearance, etc. When it's done, they can get into the elevator.
Then it's going up. On their turn, each player must express what their character is thinking about right now: how they feel, what's their problems or dreams, what they planned for the week-end, etc.
Once everybody's done, they're at level 10.
Each player can pick one other character and talk to him/her. What you tell them is again an inside thought, which can be a question, a suggestion, an advice or anything related to what has been said on level 1-10.
When everybody's done, they're at level 15. At this level, the doors open. Any player can choose to step out of the game by leaving the elevator.
Then it goes up. On their turn, each player can express one last inside thought.
When everybody's done, they're at level 20, and all players can now leave the elevator.
The game is over.