Below is a deck for a timeline activity I used on my last retrospective.
Previously I have used this approach for a collocated retrospective. I would draw a timeline on a white board, create 4 areas on the board (people, process, tools/technology, and other), and use two colors of notes (well – green /not so well - gray) to start with, followed by a third color for action items (yellow).
Here is the snapshot of the retrospective activity (this picture was generated by Google Drawing):