Civilization III didn't come with a built-in cheat mode, unlike Civilization II. Firaxis also hasn't released any official cheat codes for Civ3. The only known cheats are those tricks that exploit some bugs in the game and player-created cheat programs such as trainers and saved game editors.
Here is a list of known exploits in Civilization III. Green is allowed when playing the Game of the Month (GOTM); red is disallowed. The first five exploits listed here are allowed.
Right of Passage Abuse
Make an agreement of Right of Passage, move your units to their main cities and attack them all at once.
Free Palace Jump
When disbanding your capitol your palace will appear in the biggest other city. Your former capitol can be rebuilt by the settler it created. This way you've moved you capitol for free.
If you fill the coast of a certain island with units, even non-military, the AI won't be able to land, thus isn't able to conquer that island, until it has marines.
While at sea, you can unload a ship on the same square where there is another ship and that ship can take over the load. This way you can move your units to any location in one turn. But it takes a lot of effort.
ICS (Infinite City Sprawl)
Build a lot of cities very close next to each other. This way you simply have more cities which are in the beginning just as big as normal.
RCP (Ring City Placement)
Build several cities at equal distance from the Palace and they all have the same Rank for corruption calculations. So you can have N1 cities at Rank 1, then N2 cities at Rank N1+1 etc. This has been eliminated in Conquests, and cities at equal distance get increasing Ranks according to dates of founding.
Scout resource denial
Place a scout on a square where there is a resource and in (future) enemy territory. As long as you have peace with them you can leave him there undisturbed and the other will never be able to build a road to it.
In despotism and communism it is possible to use cities purely for unit rush building. Workers can be added to such a city and then the city can then use them to rush build units. This is disallowed, so do not create these kind of cities. Pop rushing one or two regular citizens to finish a building or to build a unit is within the rules and the spirit of the game. What is against the rules is joining workers to cities for the purpose of pop rushing.
Let all your workers join a city with a hospital and continue to build workers and let them join that city. There's no size limit so your city will become huge and you loose only one population per turn. All the workers become specialists and add to your score.
You can make cities give wealth and production at the same time. First set the cities to produce wealth. At the beginning of the next turn when another city is done building something else you can go to other cities with the arrows above and change the production of the cities that produce wealth to e.g. some unit. That will get production as well.
Rank Corruption Exploit
It is possible to move your Palace far away from the main core of your civilization, leaving your Forbidden Palace near its center. The result is that the rank component of the corruption calculation for cities nearer to the Forbidden Palace than to the Palace reduces to rank 1. The Conquests version of CivIII has been modified to eliminate this exploit. This thread discussed the ruling, which states that "You must not rebuild the palace in a location remote from the majority of your empire in order to gain a significant corruption advantage".
Black Hole of Calcutta (my name)
A city can be expanded to very high levels of population during disorder. After order is restored it then starves back to the level its food supply will support, but meanwhile it can produce lots of shields.
36000 Points in 1 Minute
Do you know you can get a score of 36,000 in Civilization III without building anything (i.e. no cities, no units, no wonders)? Here's how: Create a scenario with only mountains, where settlers cannot build cities anywhere. Play it on Deity level with as many computer opponents as you like. Since you can't build a city anywhere, skip your turn. The AI's will realize that they, too, cannot build cities and commit suicide in frustration. All enemy settlers will disband themselves on their first turns and you will score 36000 points! (Submitted by Crosmer)
Here is a list of exploits that no longer work in the latest version of Civ3, version 1.29f:
- Free Bomber Movement
When you have e.g. 10 bombers in one city, you can bombard with 9 of them and with the last one you move with "j", then all bombers move with it... should work with fighters too. This bug was fixed in v1.21f.
- "God Mode" multi.SAV
When you rename the savegame (or even save the game) including the fragment "multi" in your .SAV file, you'll be able to see the whole map and change stuff, like the production in an AI city. This bug was fixed in v1.21f.
- Unload/Upgrade Army
Stack an army along with other similar units, then use the stack movement command ("j"). The units in the army will separate and move while the army stays. You can then upgrade the units and "load" new upgraded units into the army. Note: People have reported crashes using this cheat.This bug was fixed in v1.21f.
- Bombard Anywhere
The bug allows any unit with bombardment ability to hit any square no matter how far away it is (!). All you need to do is hold the "B" key while you bombard. For example, you can destroy all the roads surrounding an enemy capital from far far away with just a few artillery units, effectively disabling the enemy's economy. This bug was fixed in v1.17f.
- Diplomacy Bug
While negotiating with a rival, ask for a huge amount of money per turn, such as 99999999. The rival will agree to any proposal! For example all her/his cities. The rival will pay the amount even though he/she doesn't have the cash. This bug was fixed in v1.17f.
Player-Created Cheat Programs
NOTE: All the cheat programs below are NOT allowed in the GOTM.
Civ III PowerBar Trainer by Crsadrjoe
This trainer lets you cheat as you play the game by showing a small cheat panel at the upper-right corner of the screen. It allows you to identify all civs currently playing, give player complete control over all civ treasuries, identifies all cities, gives players the ability to complete (at no expense) or ruin the production in any city (player's or opponent's), allows player to build a particular unit or improvement in each city with the click of a button, allows players to assign opponents to an "Enemy List" (whereby the production in each of their cities is ruined each turn). The PowerBar can be retracted upward and out of the way using the "Hide" button. It returns when the player clicks on the lower part of the bar that remains barely visible while retracted.
Civ3MultiTool by Gramphos
An integrated saved game editor allows you to edit Civ3 saved games (SAVs). Things you can change include difficulty level, year, victory conditions, reveal map, remove huts, edit/view enemy cities, kill units, change retirement year, etc. Civ3MultiTool also comes with a Civilization editor and a Civilopedia editor.
TCG Editor by hwinkels
This is also a saved game editor. It allows you to change forced retirement year, treasury gold amounts for all civs, victory conditions, player's civ within the game, reveal the entire map (multi-bug), and change the random number seed.
Civ3 Save Game Editor by Erik Tan
This editor allows the editing of all advances of multiple civilizations and city information.
Civ3 10000 Gold Trainer by Cyberman
This trainer gives you 10,000 Gold at start.
Submit a Cheat
The Civilization III War Academy contains lots of strategy and tips to help you win the game on your own. Be sure to check it out!