I do have some additional facts, gentleman. Taken from a german preview and "total war zone":

Agents:
We have to add the missionary - replaces the priest from MTW2. Religion affects further on the relationships between states.

Politics:
Distance to the capital is no longer affecting the public policy in other cities. New countries can result from revolution. Confirmed by Thamis are: Greece, Norway, Scotland and Hesse.

Units:
No more mercenaries. But as in MTW2 some special units in selected regions.

Technology:
You can build a functional rail (unlike Great Britain) if you research it.

Campaign map:
Founding of new cities isn't possible. You can play as long as you wish after the game ends. But without new tasks or technologies.

Modding:
New file system. There is no longer a "descr_strat.txt". More options for modding, but not easier: I idn't really understand thamis answer - i think it was meant this way, his answer was imprecisely on purpose.

Mange tak to Thamis, "Total War Zone" forums and 4players.de

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