Arrrgh! I see my Soviet-conquering plans falling apart!
Otherwise, what should really be changed? HOI2 and its expansions sorted out most of the major issues, and the mods fixed most that remained. Are they including more random, less event-based gameplay? (I distinctly remember the campaign I played when Japan launched an amphibious operation against the Horn of Africa... And yes, that was an NPC nation.)
Well, they might have EUIII's 'custom tag' system, so more-or-less infinite country tags available (not really infinite, of course, but far, far more then even with Armageddon).
There, ahm, was a few issues with HoI2's map, but that, for obvious reasons, won't be affecting HoI3 (mods haven't solved most of those issues, yet, since editing the map have only been possible for so long).
They haven't really revealed much about it, honestly. One could hope that they start in 1934, if one is inclined to greater preparation... or, I guess, if one wants to crush those CommieChinese and still have time to prepare for the War against Japan.
That last thing you mentioned is AI-based, not event-based
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