Custom / Melee AIs

1. They expect to start with nothing, or at least a subset of what they would have built had they started with nothing.
2. They expand when their resources run low or when their script tells them to, whichever comes first.
3. They build lots of peons expecting only 50 minerals in the bank at the start, though more would be used if provided.
4. They have some set, scripted rushes they will use, but only if there is a high chance it will end the game. It's unlikely these rushes will be used if the map maker has given the player any starting forces.
5. They attack when they see the player has expanded to a new base. They try, if they can, to target expansions to prevent the player from getting out of where they started -- "starving" the player while the AI expands, eventually building enough troops to take over the player's starting base.
6. If the player does not expand there are no scripted attacks for around 40 minutes. After that the player will get attacked whether they have expanded or not.
7. They respond to attacks in the most aggressive way they can for they are trying to "win" and don't want the player to live.

Campaign AIs

1. They expect to start with a town and do not build, but rather rebuild, and only rebuild certain things considered to be very important, like barracks.
2. They do not expand at all.
3. They build few peons and expect the map maker to have started them with a large pool of resources.
4. They have no scripted rushes and in fact do not try to kill the player. Campaign AIs are meant to be beaten.
5. They are not interested in whether the player tries to expand. They will attack anything they can find.
6. They attack with periodic scripted force compositions regardless of what the player does. When the end of the script is reached it begins to repeat a few set groups. These attacks start within minutes of the AI being started.
7. They respond to attacks lazily, allowing the player some time to destroy structures and whittle the computer down in an effort to make the game fun and give the player a chance to win.

Insane AIs

1. They make no assumptions on what they start with. They can start with one peon, or all the way up to a whole town.
2. They expand when their resources run low or when their script tells them to, whichever comes first.
3. They build lots of peons expecting only 50 minerals in the bank at the start, though more would be used if provided.
4. They always use their scripted rushes, without restrictions.
5. They attack regardless of what the player does, meaning nothing the player does can "trigger" an unusual attack or prevent them from attacking. They try, if they can, to target expansions to prevent the player from getting out of where they started -- "starving" the player while the AI expands, eventually building enough troops to take over the player's starting base.
6. They respond to attacks in the most aggressive way they can for they are trying to "win" and don't want the player to live.

Choosing the Right AI
As mentioned above, the Melee AI keys off of player expansion to know when to start being aggressive. A Melee AI may not be effective if any of the following conditions are met:

1. The player starts with a larger force than the computer.
2. The player does not have a town.
3. The player does not need to expand to secure resources.
4. There are specific conditions or triggers in the map which make it fundamentally different than a melee game.

In such cases, using the standard "Campaign AI" is preferable since it does not require any specific activities on the part of the player before it goes on the offense. Or, if you really want to threaten the player's existence, use an Insane AI script.

What about Installation levels?
The Melee and Campaign AI was designed with the standard build and expand model in mind; so they will not provide meaningful results in Installation levels. The best way to manage computer unit behavior in these situations is to use the "Suicide AI" scripts.

How do the "Set player to ally" and "set player to enemy" AI scripts work?
These scripts are obsolete with the addition of the new 'Set Alliance Status' Trigger action. Use the 'Set Alliance Status' action instead of this script, as it is more flexible and easier to use.

Can you elaborate a little on the Insane scripts?

1. The Insane AIs harvest more efficiently than the Custom ones, and spend their money much faster.
2. The attack waves within the Insane script use larger groups of units. Below are examples of the difference between Custom attack waves and Insane attack waves.

(All waves described are land attack only examples. Mileage may vary. Past performance is no guarantee of future results. People can and do lose games.)