Devoted some hours on Sunday, playing the Shimazu clan I managed to take all of Kyushu before quitting. Luckily, I haven't had the technical problems some have experienced. The campaign AI is pretty agressive, plus it cheats to make the game more difficult. Early in the game, my main rivals on Kyushu were sporting full stacks of experienced troops (3 & 4 chevrons), resulting in several battles with large amounts of casualties. They definitely didn't have time to build these armies, so I'm guessing the AI's troops automatically get the experience upgrades associated with the various buildings and tech advances. Now I've got a stack of experienced units, having earned them after many close battles with large stacks of these magically experienced troops.
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It was 1990, give or take, I don't remember
When the news of revolution hit the air
The girls hadn't even started taking down our posters
When the boys started cutting off their hair
The radio stations all decided angst was finally old enough
It ought to have a proper home
Dead, fat, or rich, nobody’s left to #%&*$#
About the goings on in self destructive zones