Small idea for a bonus unit

There will not be a lot of basic units, but knowledge that there will be many more bonus units, gives us a possibility to free our imaginations . There are many possibilies to use this system of bonus units.

Coastal artillery

This unit would have range always set to 0 (or perhaps -5, so it will still never be higher than 0) no matter which strategy is choosen. It would randomly appear after battle only in coastal cities with pretty high income. It would be of course impossible to buy this units, it's supposed to be a random bonus unit just like robo-santa . It would have small-medium defence with a quite high chance for a critical hit. It would also have defence bonus against all naval units. This would pretty much make some cities randomly better against battleship attack than other cities, and this feature would still be rather rare. What do you say?

PS. perhaps even rarer Flak Cannons could be made in the same way as Coastal Artillery. Flaks would be better when fighting off airplanes. and they would have a small chance to be found in the capital cities of Europe and in Pacific/Atlantic capitals of the United States.

Always immobile and always very rare, these units would make cities become have one additional special thing about them .

For the coastal artillery, how would you make this in a unit? Since the game is based on dragging and dropping the unit to the place you want to attack, this unit would have to be sea/air based.

I thought it was clear that this unit would not be usable in an attack, only as a defence.

What I described up there in my long post is nothing else than using bonus unit system to create something what is not supposed be a unit at all, just a random bonus to a defence of your city which you may get when you capture that city.

Sorry, I misread.