Trade/convoy/embrago

So what if some maps had a feature where a small corner of the map has several cities worth a lot.

If the game was UK, USA and China

UK has its own trade capital and has a trench/bridge like city blocking the entrance to another city worth say 999 dollars that is neutral.
The UK can't build units that can take that city but either the USA or China can.

The UK can choose to either give the city to the USA, (Trading) let it sit idle (Closed for trade) or destroy it to the point it has no value (Convoy trade)


Further there could be a gateway to the trading square that requires a lot of muscle to break into by force, and effectively capture or control the trade routes.


This could also be adapted to research a trade city that the UK has the power to 'gift to another player' and take it away at will basically constitutes a trade/research pact.

If the trade idea is shit at least the research idea is pretty good on its own, give your friends access to rare units and try to stop your enemies getting advanced tech by assaulting their trade routes (Research labs)

Friend backstabs you? Cool take away their income and/or their ability to produce OP units. (Note: Units you build to take/destroy the trade hub should have painfully low range and possibly limited to land/sea travel to avoid abuse whilst allowing you to cut down any advanced tech they have gained from you)

So say at turn 10 this city can produce spy sats, turn 15 it can produce missiles or whatever.
However if the alliance is broken, at any time the UK can decimate the trade hub and any special units it's able to produce, however the UK will be unable to take the city itself.

I draw diagram..



Also a crazy idea... (Advertise the game more DAVE)