Distribute index cards and markers. Set a topic, e.g. one of the following:
How did you feel during the iteration?
What was the most remarkable moment?
What was the biggest problem?
What did you long for?
If the last iteration had been a circus performance, what part did you play? Juggler, funambulist, clown, knife-thrower, ...
Ask the team members to draw their answer. Post all drawings on a whiteboard. For each drawing let people guess what it means, before the artist explains it. Metaphors open new viewpoints and create a shared understanding.
Set up a 'retrospective mailbox' at the beginning of the iteration. Whenever something significant happens or someone has an idea for improvement, they write it down and 'post' it. (Alternatively the 'mailbox' can be a visible place. This can spark discussion during the iteration.) Go through the notes and discuss them. A mailbox is great for long iterations and forgetful teams.
Hand out pens and sticky notes. Ask everyone for ideas on how to turn the next iteration / release into a certain desaster - one idea per note. When everyone's finished writing, hang up all stickies and walk through them. Identify and discuss themes. In the next phase turn these negative actions into their opposite.
A good debriefing deepens understanding, learning and sharing. Preparation: Download and assemble the Debriefing Cube and cards.
During the retrospective, roll the cube. Then draw a card from the category it shows and use it to prompt a discussion. Repeat as time permits.
This will broaden your debriefing options and is especially great for groups without a facilitator to enable them to effectively debrief on their own.