My experience with AI is somewhat limited too but I've done a fair amount of "forced" attack manipulation without the use of EUD triggers (which aren't very beginner friendly).
Important Things:
- Most AI scripts are generally very "weak" unit attacks with massive delays. Campaign AIs are generally an exception as they attack more often and usually with higher numbers. (Side Note: Easy and Hard Zerg AI are basically identical, which is probably a bug/oversight from Blizzard's size)
- The AI often is expected to start with multitude of resources, bases, and possibly some tech structures. If certain requirements are not met, they can stall trying to perform an "impossible task.
- Ensure the AI script matches the Computer's Race. This is important (I originally thought it didn't matter)
Weird Things I noticed:
- Sometimes, certain AIs really bug out (I have no idea why. This is extremely rare, but sometimes the AI can get stuck in a loop. You may want to test the same thing multiple times if this happens) This can also be due with supply limit stuff too (and is most likely to happen with Insane AI)
- The AI targeting attack waves seem somewhat "random." I don't know how it chooses but the AI will seem to "randomly" select an enemy target, and then proceed to clear the area of structures. If they don't attack certain locations, it could be because there are no enemy structures in that location. Furthermore, beware of invulnerable structures as some attack waves may get stuck "attempting" to kill said invulnerable structures and just stack on top of it.
Things You Can Do:
Easy Way: Create a set of units at a location and order them to patrol to an area. Once the area is clear, tell the same units to go to the next location. If you want, you can either use multiple AIs (Such as the Base is owned by CPU 1 but that "forced" attack wave is CPU 2 with "created" units ordered to attack a location and so on). Can also use "Hero" units with same stats as the normal units as substitutes instead.
Moderate Way: Create certain units with "animations" (like unburrow from a location) and then order them to attack a location. Also create a "town" location of the desired spot to attack and Center a Location onto the structures on that "town." Order units to patrol to that location. This effect makes it so units will then attack to the new location until all the structures in the "town" location are destroyed (leaving none behind).
Hard Way: Create units with animation (or no animation) at production facilities under CPU 2 command. (Whether its Hatchery, you can unburrow units, or create Marines at a barracks). Create a countdown timer that instead "randomly" generates a unit (such as every 20 seconds, 75% chance to produce marine, 25% firebat) and add incrementing counter for each time this happens. Add a second random trigger where at desired counter, there is a 50% chance the units will attack and reset the incrementing counter. Ensure CPU 2 is same color as CPU 1 (so you can't tell difference). Attack pattern can follow "moderate" way of attacking (however, you can have the origin point of where the units gather mixed by creating 4 different attacking positions too). Ensure that when the structure is destroyed, the spawn trigger is disabled. You can also set a counter for the "patrol" commander to prevent the AI units from "freezing" or "stutter stepping" in an unnatural way.
I've done with before with scouts, where originally the scouts would just attack immediately when created. Then I modified it to a incremental counter where the scouts would bundle up until 5 or so rounds of scouts were made. After 5 attack waves, the amount of scouts (or rate of spawn) would increase to 7 - 8 scouts and even sometimes 4 scouts and a carrier, and their attack position came from 4 different angled positions on the map to make it feel more like an AI attack wave. I will mention this process can be slightly tedious.
Hope these "bootleg" suggestions help. These were my own solutions to problems I had. If you are unsure what "counters" are, you can look up Death Triggers. Most stuff that I've found on StarEdit // Wikis can be useful (although I only read them AFTER I figured them out myself already)
None.