This is a format for a group retrospective. It is based on the "2-5-1" system, but has been adapted somewhat.
Note that the meanings typically associated with different fingers vary from culture to culture. The meanings listed here will be intuitive for some, but non-intuitive, or even counter-intuitive for others. Also, some people might find the reference to the "middle finger" gesture to be distasteful. Keep those potential issues in mind if you are considering experimenting with this.
Each person is requested to come up with 1 topic for each finger on their hand, based on these meanings:
Thumb
"Thumbs-up". Something that went well.
Index finger
The ONE thing that people should realize from this retrospective.
Middle finger
Something that did not go well.
Ring finger
Something about relationships. Between team members; with management; between teams, etc.
Pinky finger
Something (good or bad) that could easily be overlooked.