The 'fortified bonus' is a different one. This extra 50% (100% at cities with pop>=8) is summed to the wall bonus (wall is halved to 100% in this ruleset). The total city defense is similar to default ruleset, but here cities receive some wall bonus for free, and large cities receive an extra bonus:
LAND BASE (+WALL) (+GREAT WALL)
Town (Pop<8) +50% +150%(-) +200%(=)
City (Pop>=8) +100% +200%(=) +250%(+)
SEA/TRIREME BASE (+COASTAL DEFENSE)
Town (Pop<8) +0% +100%(=)
City (Pop>=8) +50% +150%(+)
All the values in the table represent the "wall effect" (all wall bonuses are summed, it is the way ruleset effects behave). The total wall effect is then multiplied x 1.5 (fortified bonus) x Veterancy x Terrain ...
So, when the table says +200%, it means x3(walls) x 1.5(fortified) = 4.5 (same than default)
In case of attacking sea units, the table represent the Coastal Defense. It means that large cities receive x1.5 bonus even if there is no Coastal Defense. Once the Coastal Defense is built, they receive x2.5.
I hope it is not too complicated. It might be simplified for future versions if people find it confusing. I do not think it has a big effect on multiplayer games, those bonuses was mostly designed to make the AI less dependant on buildings to defend.
Last edited by bardo on Tue May 01, 2012 7:15 pm, edited 1 time in total.