Supply

Whilst units in the Civilisation series cost resources to support, there are no supply lines, an no way to cut a unit off from supply. Advanced Tactics (and People's Tactics) have a much better supply model, but one that borders on the complicated.

A simpler model would have units supplied by their home province if a supply line is available. If not, the unit is supplied by the nearest province of the same civilisation (forcing production of that province to supply), and if that is not available (e.g. the unit is cut off from the rest of the civilisation) the unit's supply is not renewed and its readiness drops.

Simple supply system, inspired by XConq

• • Units have supply amount, supply consumed per turn, supply storage maximum

  • All highly populated tiles automatically repopulate with supply all units on them

  • Ocean tiles and sparsely populated tiles do not repopulate units with supply

  • When units' supply runs out they cannot act

  • Possibly separate supply and ammunition

What do you want the player to experience? That units caught behind enemy lines run out of supply? That naval units cannot travel / attack indefinitely without a return to port? That bases are important?