The Random Number Generator, or RNG, is the computing method that Golden Sun and Golden Sun: The Lost Age use to determine the occurrence of seemingly random events in the game, such as chance monster battles and the chances of said monsters dropping rare items. The games use separate RNG calculators for in battle and out of battle events.
GameFAQs has a guide detailing the system (this guide also contain pre-determined methods for obtaining items).
The Random Number Generator is not as random as its name would suggest, and it actually relies on player actions to determine the "random" events. As such, by utilizing the Random Number Generator, the game can be manipulated in a way to achieve a desired outcome (a monster dropping a rare item, for instance) 100% of the time, if the correct methods are followed.
It is important to note that if you have cursed equipment on any of your active characters, RNG manipulation might not work as intended. As a workaround, the Cleric's Ring seems to prevent the random numbers from advancing, presumably because the "Cursed" status is overridden in combat.
In its simplest explanation, enemy drops are determined by the set of actions that occur during combat. The game starts with a preprogrammed seed value on a hard reset, which then changes according to a set formula - each kind of action in battle causes a different number of "steps" to occur on this function. The result is that if one knows how many "steps" the function has taken, the value of the random number generator can be determined - the only thing that one needs to know, therefore, is how many "steps" have been taken. When the game begins following a hard reset, the game starts with "0 RNs", which also guarantees that the party will get a first strike on their first random encounter following a hard reset. The magic number for an enemy to drop their item is RN 31. However, the process of guaranteeing an item drop is slightly more complicated than this.
The Djinn Method
The Djinn Method is a way to make rare item drops more common.
- Killing a monster with a Djinni.
- The Djinni must be of the element that monster has the lowest resistance to; if a monster has 127 Venus resist, 100 each Mercury and Mars resist, and 48 Jupiter resist (In other words, the Mad Demon), you must kill it with a Jupiter Djinni.
- The character that unleashes the Djinni must have a higher power in that element than the monster has resistance; not normally a problem, except with the Mad Demon. Often when killing the Mad Demon, it is necessary to have a Jupiter Adept unleash the fatal Djinni.
The Djinn method works by lowering the rarity of an item in the game's internal classification method, allowing it to be acquired more easily. The result is that any monster that is killed with a Djinni of the element they are weak to and dies on the 31st RN is guaranteed to drop its item, regardless of its rarity.
Also, switching to another screen would change the enemy that's going to appear. So if you can't find the enemy you want, go to another screen and walk around until the enemy you want appears. If you somehow fail to get the item, reset again and follow the same path you originally did.
Using the RNG
Manipulation of the RNG is far simpler than all this makes it sound. It is easiest to think of the value as starting at 0 and counting up towards 31. Each action increases the count by a certain value, as follows:
- First strike in battle: 1 RN
- Attack Psynergy: 2 RN per target
- Healing Psynergy: 2 RN per party member targeted
- Support Psynergy: 1 RN per party member targeted
- Status Psynergy: 1 RN per target
- Defend: 0 RN
- Attack Djinni: 2 RN (3 RN if the enemy is weak to that element)
- Enemy Actions: 1 RN per enemy on the field - 2 instead for each Phoenix and Fire Bird enemy, 3 for each Wonder Bird. Even though the enemy does nothing on its 1st turn, RN is added between the 1st and 2nd of your turns.
- Enemy Death: 1 RN
Note that on the enemy's turn, RN is added depending on how many enemies are left on the field that turn even if it is a "first strike" in battle. For example, if there is 3 enemies of which none are Phoenix, Fire Bird or Wonder Bird, 3 RN is added during the enemy's turn before your 2nd turn even though the enemy did not attack. Also, enemies that have been killed do not add to the RN.
A Djinn Kill would consume a total of 3 RN with the addition of the enemy's death, for a total of 4 RN.
There are 2 RN numbers that can be used to receive items using the Djinn Method: 27 RN and 31 RN. These two RNs can be used to drop any item. However, 27 RN does not work on drops like Kikuichimonji, Lachesis' Rule or Tisiphone Edge. (This is due to its drop rate of 1.6% when using the Djinn Kill 3.2% or higher is required for 27 RN to work). An enemy's death on 31 RN is guaranteed to drop its item.
Also, equipment that affects speed is helpful when manipulating the RN. Either to boost the speed of your party against the enemy or reduce the speed of one character who would perform the Djinn Kill.
Since the enemy dies on 31 RN, the Djinni attacks on 27 RN, and a first strike takes 1 RN, the number of RNs the party needs to "consume" during battles depends on the number of enemies participating:
- 1 Enemy: 25 RNs
- 2 Enemy: 24 RNs
- 3 Enemy: 23 RNs
The simplest method is the one with two enemies, which includes nearly every battle in which an enemy of interest to RNG manipulation can be encountered. For this, the party simply needs to use four attack Psynergy on the first turn (1 + 4 + 4 + 4 + 4 = 17 RN), followed by two more on the second turn (17 + 2 + 4 + 4 = 27 RN), then unleashing a Djinni of the element the enemy is weak to for the kill (27 + 4 = 31 RN). The other enemy should still be alive after this. Also, as long as the item drop is not any of the equipment mentioned above, 27 RN can also be used, which means you can set one party member to defend and use only one attack Psynergy followed by a djinn on the 2nd turn.
If the enemies can't withstand 6 attack Psynergy, or if the party member with the appropriate Djinni is too fast, Wish or Aura can be used in place of two attack Psynergy. To make sure enemies can withstand all six Psynergy attacks, use the weakest Psynergy available (Quake, Flare, ect), just make sure the attack Djinn will kill it. For one or three enemies, one Support or Status Psynergy (such as Impact) must be used. Regardless of method, as long as the appropriate number of RNs are consumed before the Djinni is unleashed, the enemy will drop its item with 100% certainty.
Save the game and do a hard reset in the area where the monster that drops the item you need appears. Run around to get in a battle. If the encounter consists of a formation of 2 monsters, with at least one of them being the monster you want, proceed. If not, you might want to do another hard reset and try again. The "step counter" that determines when a random encounter will appear is preserved even after a hard reset, so it may be worth it to run around a bit, save, and repeat; this will ensure a random encounter happens very shortly after reloading, which can save a lot of time if the area in question has a lot of different enemies, or if the enemy you want can appear in 1 or 3 monster formations.
During battle, have the entire party use multi-targetting Psynergy on the targets in the first turn, and since a battle right after a hard reset always involve your party attacking first where possible, the monsters will not be able to act. During the second turn, use two multi-targetting Psynergy on the enemies, and have the third party member (or fourth, if one of the three party members that act before uses Defend) unleash an attack Djinni of the element the monster is weak to on the monster. If by this point, the monster flashes in colour and dies, you will obtain the drop of that monster at the end of the battle, however rare it is. If the monster does not die then (either dies too soon or doesn't die by this step), adjust the power of your attacks until you get it just right.
This method works as long as your party members are all faster than your enemies, and there is no monster that can act multiple rounds per turn on the other side. You may also need to juggle Djinn around your party in order to make sure the member with the killing Djinni is slow enough to act third or last.
Level RNG (GS1 only)
The general trend in the Golden Sun series, like all RPGs, is that you grow stronger as you level up. However, in the first game the RNG can be exploited to produce higher stat increases per level. This has one immediate effect, and one long term effect; with higher stats, you can choose to level less during a complete run through. The second, long term effect of using Level RNG methods is passing these RNG'd stats over to the second game, where the RNG methods shown below don't work. It's easiest to explain by example: Let us start with Isaac. In GS1 a typical level up for Isaac would look something like this (in the order of HP / PP / Attack / Defense / Agility)
7 / 3 / 4 / 2 / 3
However, by exploiting the RNG, you can get a perfect level up like this:
8 / 3 / 4 / 2 / 4
Perfect level ups like this are different for each playable character; go here for the full list by level.
By leveling up randomly, it is possible to achieve perfect level ups, but perfect leveling becomes increasingly harder the higher level you are.
Level RNG Methods
The general method for Level RNG is saving in an area, resetting, getting into a battle with an enemy, and finally killing it. (Note that when resetting it doesn't have to be a hard reset like item RNG, soft resets work too, but attacking first or being surprised by the enemy during battle DOES affect the outcome of this method). Here's the trick: It's how you kill the enemy that affects what level up numbers you receive. This is the list of what effects the numbers upon killing an enemy:
For most cases when using item RNG, you want to stick to Attacking and offensive Psynergy for the best results. (The values you get upon level up do depend upon which enemy you kill to receive the necessary experience points required to reach the next level)
The following method is for a Perfect level up (Guaranteed to work) for Isaac: For this to work, Isaac needs to have the Ninja Blade as his weapon (It can be on anyone who can wield it, but for this example it will be equipped on Isaac), he needs to be missing 10 EXP or less to the next level, and has to be in the first room of Goma Cave (The one where you have use Move to knock down the rock blocking the path). You would save, soft reset, then run around to get into a battle. The first monster you encounter should be a single Skeleton. If you attack first, or if the Skeleton surprised your party, soft reset and try again, as this method requires a standard start. If it is a normal start, have Isaac attack the Skeleton (with the Ninja Blade), and everyone else defend. If done correctly and the skeleton dies, regardless of what happened (Unleash, critical hit or normal attack) Isaac should receive something similar to the following level up:
HP boost +8 PP boost +3 Attack boost +4 Defense boost +2 Agility boost +4
In other words, a perfect level up. Note that the maximum numbers you can get from methods like these go down the higher level you are, so that if you are above level 39 the PP boost would be +2 instead of +3, etc.