This is a step by step set of instructions for those confident to make advanced changes to their firewall. I have windows 7 home premium 64-bit, so these changes are made in any windows 7 machine, and probably vista too.any changes you make are your responsibility, i can't be responsible if you make a mistake, though i am happy to help anyone with problems.
here is the guide:
1.open up 'windows firewall with advanced security'
2.go to 'inbound rules' section
3.sort by name, so all napoleon total war rules are grouped
4.right click on the first rule, and go 'properties'
5.under the 'protocols and ports' tab, select the combo box which by default says:'udp', under the heading 'protocol type'
6.from this combo box, select 'any'. at the bottom of the dialog box click apply.
7.repeat this for the rest of the entries under napoleon total war.
8.if necessary, repeat for entries under 'steam'
9.now go back to your napoleon total war entries, select properties, and go to the 'advanced' tab
10.under the 'edge traversal' section, select the combo box. select either 'allow edge traversal' or 'defer to application', both have the same effect here. click apply.
11.repeat for the rest of the entries under napoleon total war.
12.if necessary, repeat for entries under 'steam'