This is something I’ve struggled with–a good method for storyboarding branching scenarios. I’ve used several different Word and PowerPoint templates in the past, none of which have quite worked the way I wanted. I can write the branching in a linear document without much trouble (I once drafted one longhand in a notebook), but it makes my SMEs brains explode to try to follow them. I’ve seen recommendations for Twine in the past, and this explains in more detail how it works as a storyboarding tool.
Nicole Legault explains how she built a branching scenario in Storyline 2 in about 6 hours. She explains her process for building and saving time, along with details on creating a progress meter and where she found images.