I wish survivors will be improved their AI.
When a survivor attacking enemy, he rarely carries out a move command. After a lot of clicks, he finally moves.
Sometimes a survivor can't shoot to enemy in front of him. Also he fire his weapon to wall or gate when zerg is behind it.
Most of all, my survivors follow other players too frequently. Their following target is not fixed, but changing very easily. Taking survivors is tiring competition with other players. Increasing the number of total survivor spawning will reduce this bother.