First let me say that it might make sense to place options like the victory condition and allowing favor items in the main lobby. In many games the options like creep spawn rate and starting levels wont be touched by the players. And the other gameplay modi might be used more often too.

Back to the game modus Fortress:

• The fortresses in the middle should be moved back a little bit in my opinion. This would allow the players to fight for the experiance flag without getting shot at by the fortresses. Otherwise it might become a stand off between demigod with range damage.

• Creeps are currently avoiding the fortresses and are running past them to the enemy Citadell. Thats not a big issue as long as Catapultsauri are not present but right now the creeps are useless (except as XP source).

• Range of the fortresses should be increased slightly. Regulus with range 3 can outrange them, that might be a little OP (he can still use his sniper skill anyway).

• Fortress strength could be increased to balance for the additional creeps, either by more HP or faster regeneration.

Maybe you can add a new path marker for this victory condition to guide the creeps? That way you could adjust their path without interfering with the other game modi.