The various civ games have treated fresh water as an infinite resource. Once you find a single source of fresh water, you can basically irrigate your whole civilization. I think water should be treated as a limited resource. People in cities consume some water. Irrigation consumes more water. You can get fresh water from rivers, lakes, and desalinization plants. If you take water from a river, there should be less available downstream. It should be possible to take all of the water from a river, thus drying it up for anyone downstream. You should be able to drain a lake in a similar fashion.
Water is a precious, precious commodity. I don't know if there have been any wars fought over water, but experts predict there will be (google "wars over water"). The western states of the US bicker constantly about water rights. Just in California, there are big fights between cities like Los Angeles and farmers who rely on lots of water to grow winter strawberries in what used to be desert. Then there's the draining of the Aral Sea in Central Asia.
Civilization games have had aqueducts, but we've never paid attention to where the water comes from. An aqueduct isn't a well, after all. Maybe cities start with a well that puts out some amount of water, but if you want more, you have to build an aqueduct to a lake or river (or be next to a lake or river). If you put out too much pollution, you should have less fresh water available. Cities downstream should suffer if your sewers empty directly into the river. If you build a wastewater treatment plant, that problem disappears. You can attack another civilization through water, by draining rivers before they get to them, by polluting their water, or by destroying their wastewater and desalinization plants. Thus, you could replace the arbitrary city size limits of civ3 with something a little more sensible. Perhaps it could tie into the civ4 concept of health. One of the biggest problems facing the Third World today is lack of access to clean water.
On a related subject, I would change how farming works. The vast majority of farms over the vast majority of human history have not been irrigated. Instead, farmers have had to rely on the rains. Look at what happens to India when the monsoon is weak. You shouldn't have to have irrigation to make a tile produce more food. Instead, you should be able to build a simple farm improvement. That represents plowing fields, sowing crops, keeping animals away, etc., but not irrigation. Farms increase food production a bit. Food from unfarmed land represents people wandering around and gathering whatever grows wild. If you have the technology (Construction?) to irrigate and access to a supply of fresh water, then you can irrigate your farmed fields and get even more food. In the late Industrial era, you can mechanize your farms, which uses oil and even more water to produce even more food.
On another related subject, I think units in the desert should risk getting hurt due to lack of fresh water. On the plus side, this makes oases something real, not just a rare form of desert. An oasis is a source of water in the desert that you can tap for a city or to irrigate some fields. In a large desert, it's a strategic location where units can rest without being baked under the sun in unforgiving terrain.
Water is a precious, precious commodity. I don't know if there have been any wars fought over water, but experts predict there will be (google "wars over water"). The western states of the US bicker constantly about water rights. Just in California, there are big fights between cities like Los Angeles and farmers who rely on lots of water to grow winter strawberries in what used to be desert. Then there's the draining of the Aral Sea in Central Asia.
Civilization games have had aqueducts, but we've never paid attention to where the water comes from. An aqueduct isn't a well, after all. Maybe cities start with a well that puts out some amount of water, but if you want more, you have to build an aqueduct to a lake or river (or be next to a lake or river). If you put out too much pollution, you should have less fresh water available. Cities downstream should suffer if your sewers empty directly into the river. If you build a wastewater treatment plant, that problem disappears. You can attack another civilization through water, by draining rivers before they get to them, by polluting their water, or by destroying their wastewater and desalinization plants. Thus, you could replace the arbitrary city size limits of civ3 with something a little more sensible. Perhaps it could tie into the civ4 concept of health. One of the biggest problems facing the Third World today is lack of access to clean water.
On a related subject, I would change how farming works. The vast majority of farms over the vast majority of human history have not been irrigated. Instead, farmers have had to rely on the rains. Look at what happens to India when the monsoon is weak. You shouldn't have to have irrigation to make a tile produce more food. Instead, you should be able to build a simple farm improvement. That represents plowing fields, sowing crops, keeping animals away, etc., but not irrigation. Farms increase food production a bit. Food from unfarmed land represents people wandering around and gathering whatever grows wild. If you have the technology (Construction?) to irrigate and access to a supply of fresh water, then you can irrigate your farmed fields and get even more food. In the late Industrial era, you can mechanize your farms, which uses oil and even more water to produce even more food.
On another related subject, I think units in the desert should risk getting hurt due to lack of fresh water. On the plus side, this makes oases something real, not just a rare form of desert. An oasis is a source of water in the desert that you can tap for a city or to irrigate some fields. In a large desert, it's a strategic location where units can rest without being baked under the sun in unforgiving terrain.