I'm looking for the name of a chart type that (I think) is used in Scrum.
It's a spiral where each revolution represents a sprint and the radius at any given point is the amount of work remaining. The spiral is overlaid on top of a series of concentric circles representing the amount of work remaining.
Does anybody have any clue what I'm on about?
Just a shot in the dark...
The only one I can think of is a risk management approach (not specific to agile or any of the SDLCs). It's called the Spiral Model. It's totally not what you're talking about, but there are some similarities (mostly passage of time as you move away from the center.
Beyond that... Fifteen years of Scrum, and I've never seen what you describe. Is it possible it was from some internal slide deck at your organization?
This sounds like a custom chart that someone has designed. I can imagine how it looks with an ever-decreasing remaining scope towards a bulls-eye.
Although the regular burn-up charts are fit for purpose; I can see how an enterprising member of the team might have designed it.
The alternative explanation is that it is one of the custom charts produced by Aha! - the product roadmapping company which now offer additional services beyond their original purpose of visual product roadmaps. I have only ever used Aha in a trial basis so I cannot say for certain. I also make no recommendation for their product whatsoever.
They have various visual plans including one which looks like the following. If you cannot find your custom chart, you might be looking at something from this software vendor.
