I've used the technique of Story Mapping countless times at project inception to assist in understanding the problem domain area, ensuing a shared understanding of the problem and a collaborative approach to building a product backlog. Unfortunately I can't really claim any credit for this methodology!!
Story mapping starts with an overarching vision of what's required... And is then broken down to a more granular level.
I did this exercise with a large well known e-commerce brand...... Working on high level user journeys within the system- Done with blue index cards - The colour isn't important.. But it's nice to visually see the different types of stories/epics or NFR's (Non functional requirements)
Browse the catalogue
Add to basket
Each section was then broken down into smaller stories.... So Payment was broken into different ways of paying
We then tried to find the simplest user journey which took us through the entire system.... drew a line and move everything story which wasn't part of this journey below...
We then began an exercise of iteration release planning.... The teams would be working in 2 weekly sprints with the view of each programme increment being 5 sprints....
We then began to work out what users stories we'd aim to complete in each PI (Programme Increment)
Story mapping is great for project inception... It's allows a backlog of items to be quickly built in a very visual structured way. It creates a shared understanding of what's required and what we're building.
It's also a brilliant way for slicing work into increments... Which also allows us to monitor progress and adjust our release planning!!!