How the heck can you manipulate RNG in the GBA trilogy.

[Seo]

Hello there ! How are you doing guys ?

I must point something in order to have my spirit cleared from it once and for all and just to die in peace so it's finally understood.

Let's take a look at the court record... wait wrong game.

Let's clearly point HOW the RNG works in Fire Emblem Sword Of Seals, Blazing Sword, and The Sacred Stones.

The case here is more The Sacred Stones because I'm currently leveling Gilliam as a General and try to use RNG at my advantage.

What I understood so far is :

The RNG, also known as Random Number Generator, is an algorithm that likes the name implies, sorts a number randomly choosen.

The number can be else from 0 to 50 or from 51 to 100.

These RNs are sorted for each of these values in the game :

The Hit Accuracy : Two RNs are sorted in order to have an average and if the average is a value under the Hit Accuary's value, your unit WILL hit.

For example, if Lyn's hit is 60 and when two RNs for the Hit are sorted, if the average of these two RNs is below 60, Lyn will hit, is it right ?

The Critical : The 3rd RN sorted will go for the Crit, if you got a RN below the number of your Crit rate, you will do a critical hit.

It also manages which stats are uped when a level up happens. I guess it's something like 7 RNs that are used respectively for the HPs, Str, Skl, Spd, Lck, Def, Res.

Now, what I guess to be right about manipulating the RNG in the GBA games is :

In fact it's not really like a manipulation. It's like you know if the RN sorted is under 50 or if it is above.

And it works like this, to know it, you must make move a unit and make that unit take a specific pattern of movement that will cause the arrow pointing to where the unit is going to choose two alternatives :

The first one is : The arrow is pointing towards up or down.

The second one is : The arrow is pointing towards left or right.

If you have an arrow pointing towards left or right, you can be sure that the RN you sorted is between 0 and 50.

But if it is pointing towards up or down, your RN will be between 51 and 100.

So about manipulating RNG, does it work like this ?

I want to up Gilliam's Strength because he will levelup soon.

I'm at the Valni Tower and I'll kill an Entombed to get my levelup.

Meaning that if I want to be almost sure he will up his stat, I must do right before attacking the Entombed :

Have Gilliam taking a pattern that will force the arrow to choose a direction to point, either left/right/up/down.

If when I arrived where I wanted the arrow to be, the arrow points to the left or right, I press B in order to cancel my action of wanting Gilliam to move.

Then, I will know that I sorted the first RN, and this RN will be between 0 and 50. If I do it again and have the same result, I do B again, and I know that my hit rate will be anyways under 50, so Gilliam will hit, right ?

So in order to up Gilliam's strenght, I must :

Make the arrow take a pattern that'll force her to point to the left or the right, and this, five consecutives times ?

Because making it five times will sort the two first RNs for the hit rate, then the 3rd will be for the crit, then the 4th will be for the HP or not levelup, then the fifth will be for the strength levelup, right ?

But what I don't understand is this : I did all of that and however, Gilliam didn't up his Str. His STR Growth Rate is of 45, so there is two possibilites :

-Or I'm really a bad lucky guy, and every RN that was sorted when the arrow was pointing to the right/left was above 45 (which is not impossible because of what I understood, when this occurs, the RN sorted is between 0 and 50. So to have RNs of 46, 47, 48, 49, and 50 is not impossible.

-Or I'm really messed up and understood everything in the wrong way.

Please help me, people that know it clearly, that makes me mad ! ><

Edited October 30, 2015 by Seo

[Paper Jam]

The RNG doesn't really "generate" random numbers; it's actually a very long sequence of pre-determined, seemingly random numbers that are nonetheless predictable if you use save states / Restore points, or even if you just restart the level.

There are several actions that "burn" random numbers.

Each attack that misses burns 2 random numbers (which were used to determine whether the attack would hit or not).

Each attack that hits (but doesn't crit) burns 3 random numbers (the aforementioned two to determine whether it hits, plus one more to determine whether it crits)

Each attack that results in a critical hit or a Silencer burns 4 random numbers (2 to determine whether it hit, 1 to determine whether it was critical, and 1 to determine whether Silencer activates... whether the character making the critical hit is an Assassin or not).

Each level-up burns 7 random numbers (to determine whether HP, Strength/Magic, Skill, Speed, Defense, Resistance, and Luck increase with the level-up--in that order).

In addition to this, random numbers are burned whenever the AI needs to create a path for an enemy or AI unit if there is more than one possibility, e.g. with "diagonal" moves. If the AI wants to move an enemy unit one space down and one space right, one Random Number will be burned to determine whether the unit first moves down, then right, or whether it first moves right, then down.

By the same token, you can force the AI to create a path for you with any unit that has an odd number of Movement points, but most easily with Pegasus Knights (or Cormag, once you get him). Take Vanessa, for example, with open spaces on all sides: If you select her and move the cursor one space left, one space down, two spaces right, two spaces up, and two spaces left, you'll force the AI to create a new path for her to the space one up and one left from her current position, and the Random Number will determine whether that path is first horizontal and then vertical, or first vertical and then horizontal. (I think 50 or higher will result in the former, while lower than 50 will result in the latter.)

The most important thing to remember about all of this is that the numbers are not generated as they are needed; instead, they cycle through a predetermined sequence. If you burn the exact same numbers by doing the exact same things in the exact same order, you are guaranteed to get the exact same results.

[Mekkah]

https://www.youtube.com/watch?v=wIr7pDj-S2I

Here's a video.

[Seo]

Thousands thanks for the video, but something bothers me...

He said that he exactly burnt 1 random number.

However, Paper Jam said that a critical hit burns exactly 4 random numbers. How then did he knew he was about to land a critical hit ?

And even if he burnt the numbers, that would have basically meant he got a RN between 1 and 50, so how could he've been sure about the fact he would anyway land a critical hit ?

[Gradivus.]

silencer skill in FE7/8 burns an RN regardless of who crits to determine if a silencer procs. Every hit also burns 3 RNs (2 for the hit, 1 for crit), even if the crit rate is 0.

Edited November 1, 2015 by Gradivus.