The Let's Play Archive

Etrian Odyssey

by Crosspeice

Part 44: AI, eh?

Side Course 03: AI, eh?

Etrian Odyssey is quite a simple game, and that's something that's really shown with the various encounters. Well, mostly. AI in this game is pretty easy to follow and pretty damn important in some cases, while I'm paying zero attention to AI for regular battles, especially for FOEs where they are usually very simple, some Bosses have AI that you really need to be wary of. Of course, you can only find this within the game's data itself, but there's a fair few things to go over.

First, every enemy has Checks that go in order, with various Conditions within that check. Here's the Wolf's first check, since it's the first enemy ordered in the data:

It goes down the list and checks whether it's true or not, 1 if true, 0 if false, and then the binary combination leads to a specific Attack Table, which we'll get to in a moment. Pretty self explanatory, though the game's internal turn count starts at 0, so keep that in mind for enemies that do something on the first turn, or in a blindside. There are a LOT of conditions and a fair few will never even happen, either due to rare circumstance, or bugs. Cause there's a lot of bugs in the AI, as we'll see later.

Anyway, it's very rare that all three of these checks will occur at the same time and they don't even need thinking about, since it only leads to 3 different results and various combinations of the different conditions result in the same thing anyway, such as the case of 100 and 011, so a lot of conditions are just fluff to make the enemy do a couple different things in different scenarios. Now, for the results that are blank, in this case 000 or 010, then it either goes to the next Check, or, if there aren't any more, to Attack Table 00, which is what the enemy always does if no conditions are fulfilled.

Alright, the first condition pops up a lot for enemies that do something on the first turn, especially if they blindside you. Remember, concurrent checks only occur if there were no conditions fulfilled in the previous check, or the fulfilled conditions led to a blank table that moves onto the next check. Since this is the final check a Wolf has, let's see those Attack Tables.

If an enemy has a lot of conditions and checks, then the number of attack tables can get very quickly out of control. So let's break this down. If no specific attack table is ever called, then it'll use 00, which usually consists of a basic skill or a melee attack. It calls upon the specific skill from the database and then chooses its target. The same skill can have different attack preferences depending on the table, as you can see there, but the specific skills that gets called (in this case Fang 0C2 (since there can be multiple versions of the same skill)) will always stay consistent for that specific enemy, bugged skills being the exception.

So, since Attack Table 1 and 2 are basically the same with only slight targetting differences, it means all the various conditions in the first check are basically pointless, since they all lead to the same thing. This isn't really something to keep in mind, you can only read this stuff here and keeping all the various combinations is pointless. So instead, we should focus on the targetting. For the most part they're pretty simple, with the most common ones being Target in Front Row, FRow Preference or Target of Phys. Class (LSPDR). This explains why your front row will take a lot of damage, though who specifically gets targetted and what the chances are is something we don't know about. Of course, there are plenty of other specific targetting for that skill, such as Target w/ Lowest HP, Random Target, or whichever target doesn't have a specific ailment, or takes the most damage from a specific element. Some of them get quite sneaky, but for the most part, it'll target the front row, so use that to your advantage.

Looking into an enemy's AI can expose a lot of what it does, or indeed, what it can only do, such as most of its attacks only targetting the front row. It can also reveal some stuff you'd never know about otherwise, such as attacks the enemy will never use due to a bug, or the conditions are way too specific, or in some very rare cases, attacks that will never be called. One example is Woodflies, which have this AI:

Bit long, but is there something that sticks out? Well, one of the checks is using Powder on the previous turn. As you can see from the attack tables, Woodflies never use Powder and indeed, no enemy uses Powder, it's an unused skill. It's in the data, uses the Head, attempts to inflict Blind on a single target with a 70% infliction chance and a 50% speed modifier. Well, we know it inflicts Blind due to one of the conditions is Target w/out Blind status. They probably thought it was a bit mean for a first floor enemy to use Blind and Head Bind. This also means the second attack table is never used, since it'll never use Powder last. Bet you also didn't know that Woodflies could run, since it only happens in very specific circumstances. So, diving into the AI tables is very interesting, especially when some enemies are a bit, well...

We'll find out soon enough.