Distribute blank index cards and tell the team they have 10 minutes to write a postcard to a person the whole team knows (i.e. an ex-colleague). When the time is up, collect and shuffle the cards before re-distributing them. Team members take turns to read out loud the postcards they got.
Let team members appreciate each other and end positively Source:
Agile Retrospectives who took it from 'The Satir Model: Family Therapy and Beyond'
Start by giving a sincere appreciation of one of the participants. It can be anything they contributed: help to the team or you, a solved problem, ...Then invite others and wait for someone to work up the nerve. Close, when no one has talked for a minute.