I think attacks and missions would be more consistent with effective goals.
For this, it is necessary for bots to take or leave artifacts or resources or whatever else.
For instance we attack a convoy:
we destroy the escort
but normally, after we could destroy the trucks of the carriers,
take resources from the trailers,
put resources in our carriers bots
(with specific bags in the slots: one for for one kind of resource. Searchable, exchangeable , removable, "droppable" and "takable" on the map)
and go back to the base.
For the missions, if the combat bots could have a container for artifacts (keys, plans of technologies or buildings, formulas for pyrotechnics or materials etc...),
we could take or leave artifacts at specific points of the map (bomb in a silo etc...)
after having defeated defense squad and or base.
With this artifacts we could research special weapons (ion cannon and ammo) or anything else.
With this we could make TRADING with other bases or towns or mining camp to improve them.
So we could travel to mine resources (having OUR convoys),
or to help building camps or towns and trade what we want.
The places could serve during all the game instead of one mission only. The monoliths on the map can become true mining camps we can travel to with buildings and hardware to install and to defend and resources to take.
I think this could give a new dimension to the game.
For the problem of multiplayers handling we could imagine private access visible only for the player to avoid complications and conflicts with other players (for the missions for instance).
And common access to towns or other places for the trading with a list of offers from the players.