His opponents who played him were sometimes mystified, though the reason often becomes clear many moves down the road. He was not afraid of starting complex fights, even ko fights, and the games often have huge swings in territory. He played in a way with great freedom. Opponents would play thinking they played a forcing move, only for Go Seigan to tenuki (play elsewhere on a board, often at strategically vital points). People have tried to replicate his style, but it is difficult to put into practice without Go Seigan’s reading skills.
Also, his given name contains the character 源, which is read "gen" in Japanese, not "gan".
This may be way outside of your wheelhouse, but I have to ask -
The Mandarin reading of 源 is yuán. The phonetics are something like [ʲyɛn]. A similar raising of the written vowel occurs in the pinyin syllable yan (e.g. 言, 严, 眼), which is [jɛn]. In other pinyin syllables, an "a" represents /a/, which is something sort of intermediate between the English PALM and TRAP vowels.
It makes perfect theoretical sense that /a/ might be realized as [ɛ] when following a high vowel. But I've always wondered whether yuan and yan really do have a phonemic /a/ there or whether there might be an /ɛ/ phoneme. And it's interesting to me that the Japanese reading of 源, presumably taken from a much older Chinese, uses /e/ there instead of /a/. Can you provide any insight?