Jack0h: If I understand your question correctly, and you can dump the game scripts somehow, like using GARbro, most VNs usually have some kind of goto/label system. For example text starting with
*
are labels and
[link target=*text]
are gotos in Kirikiri VNs.
The rest is simply dumping all the game's goto_op -> label pairs, re-labeling the unlabelled parts, marking the original files as subgraphs, and then feeding it all into Graphviz to get a nice visual decision graph (
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).
It's much easier, but requires some basic programming skills.