how about a later-game worker action: Construct/Remove Minefield (e.g. with Physics)
Works just like a terrain improvement, but is only visible to the civ that built it and has a different effect:
Units moving on the tile with the minefield receive x per cent damage, except for workers. The same goes for units of the civ that built the minefield, mines don't care about what flag you carry! Make it collateral so whole stacks can be damaged.
Also, when a worker moves with the stack onto the minefield, it will not receive any damage. The worker acts like a pioneer unit in this case. This has two advantages:
1. No need for another kind of new unit just for the minefields
2. In times of war, the building of infrastructure in a country will suffer bc resources are spent for military production. The necessity to send workers with the troops to act as pioneers resembles this fact, bc you cannot use them to improve your territory further.
I don't know how hard it is to implement this (especially so the AI can and will use it), but it would add a great strategic element to the game.
Works just like a terrain improvement, but is only visible to the civ that built it and has a different effect:
Units moving on the tile with the minefield receive x per cent damage, except for workers. The same goes for units of the civ that built the minefield, mines don't care about what flag you carry! Make it collateral so whole stacks can be damaged.
Also, when a worker moves with the stack onto the minefield, it will not receive any damage. The worker acts like a pioneer unit in this case. This has two advantages:
1. No need for another kind of new unit just for the minefields
2. In times of war, the building of infrastructure in a country will suffer bc resources are spent for military production. The necessity to send workers with the troops to act as pioneers resembles this fact, bc you cannot use them to improve your territory further.
I don't know how hard it is to implement this (especially so the AI can and will use it), but it would add a great strategic element to the game.