3. Warfare is weird in Civ 5, you start with a very low military supply cap and early battles are usually the most fun. At some point though, the sheer amount of units makes war a boring task of chipping away at enough enemy units while not particularly caring about positioning or tactical placement. While a lowered supply cap is part of this solution, having artillery units (or range units as well) deal splash damage by default would help. I'd also consider having later game ranged units be capable of an overwatch mechanic, similar to air units ability to intercept. In any event, units seem to die too quickly to earn enough promotions to be valuable, or have too many promotions and be unstoppable. Some type of forced retreat ability, or an ability that Naval warfare and city sieges always felt strange, because you can usually capture cities but are defenseless at holding them. An unintended effect of this is that it's a great way to raze cities—every time you capture a city, you can move your melee naval unit out, have the city be recaptured (lowering its population), then recapture it again (further lowering the population), etc. until you can raze it in a turn or two. Either naval units and land units need to be merged somehow or allow them to switch between different unit types.