How to win on deity or sid in Civilization 3

Generally, you want to finish the game as fast as possible, otherwise enemies are going to overbuild/overreseach you. In order to be able to finish the map quickly, pick a small map. In order to be able to quickly get to the enemy, pick a single continent with a minimum of water mass. Set a wining condition to elimination - with this setting, it is enough to conquer a single opponent's city in order to completely eliminate the opponent. With this setting, the opponent’s biggest advantage - many settlers from the beginning, is turned into a weakness. All you need is 2 unit that are capable of overcoming 2 spearmen in a weakly defended city, and the opponent is gone. In order to maximize your advantage, pick a nation with an early unique unit. And set your opponents to nations with late unique unite. The selection of your nation depends on the game rules of your Civ mod/patch. For example, in RARR, Aztecs are awesome. Their unique unit costs the same as a warrior. But it has a bonus attack point. It has a bonus movement point. It is not penalized for movement in jungle and forest (set the map to wet climate in order to maximize this benefit). It has a bonus hit point and it can enslave. And of course it helps that you can build the unique unit from the beginning without any resource dependency and that it triggers early gold age (remember, you want to finish the game as fast as possible). If you can pick your starting position, it is good to start next to a bonus resource like game in order to maximize the population growth and unique unit production. If everything goes well, you should easily win in the first 30 turns by conquest.