Fire Emblem: The Sacred Stones

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Intelligent Systems developed Fire Emblem: The Sacred Stones for the Game Boy Advance. The code read here is the FireEmblemUniverse fireemblem8u decompilation, which builds the North American ROM.

Its forecast window shows one hit percentage, and the game rolls against it with the average of two random numbers¹. Computed from the code, taking the two rolls as independent, a shown 80 hits 92.2% of the time and a shown 20 only 8.2%². A critical hit rolls a single number³. A level-up rolls one number per stat, and rerolls up to twice when no stat rises⁴.

Mechanics

Mechanic	Kind	How
Hit chance	Two rolls averaged	hit less avoid, against the average of two numbers from 0 to 99, so a shown 80 hits 92.2% of the time, computed with the two rolls taken as independent
Critical hit	Weapon and stats	the weapon's crit plus half the attacker's skill, less the defender's luck, on one roll; a critical triples the damage
Weapon triangle	Hit and damage	15 hit and 1 damage each way, for swords, axes, and lances and for anima, light, and dark
Follow-up attack	Speed threshold	an attack speed 4 or more above the foe's strikes once more after both have attacked
Growth rate	A roll per stat · player units	each level rolls each of seven stats on the character's own percentage
Growth rate	Growth times levels · autoleveled enemies	one roll per stat on the class's growth times its levels, moved by up to an eighth
Permadeath	Per unit	a player unit that falls in combat is flagged dead, and chapter changes keep the flag; a phantom is erased
Damage formula	Attack minus defense, no roll	might, triangle, and strength less defense, tripled on a critical and held within 0–127

Every claim about this game, by concept (11)

Critical hit	In the North American build, a unit's crit is its weapon's crit plus half its skill, plus 15 for classes with a crit bonus; the crit shown and rolled is that less the defender's luck, at least 0, and one random number from 0 to 99 below it triples the hit's damage.	Code
Damage formula	In the North American build, damage is attack less defense, where attack is the weapon's might plus the triangle's damage bonus, tripled when the attacker or its weapon is effective against the target (doubled instead when the effective weapon is one of eight legendary weapons), plus the attacker's strength, and defense is terrain defense plus Defense, or terrain resistance plus Resistance against magic; no roll changes it except two skills, Pierce (which sets defense to 0) and Great Shield (which sets the damage to 0); a critical triples it, and the result is held within 0–127.	Code
Follow-up attack	In the North American build, a battle runs the attacker's round, then the defender's counter, then one follow-up round by the unit whose attack speed beats the other's by 4 or more; attack speed is speed less the weapon's weight beyond constitution, at least 0.	Code
Growth rate	In the North American build, a level-up rolls each of seven stats on the character's own growth rate, with one random number from 0 to 99; each full 100 of a rate is a sure point, and if no stat rises, the game rerolls the stats in order up to twice, stopping at the first that does.	Code
Growth rate	In the North American build, a non-player unit placed with autoleveling, unless it is a boss or its character number is below 0x40, adds to each stat one roll on its class's growth times its levels above 1, moved at random by up to an eighth of that product either way.	Code
Hit chance	In the North American build, an attack hits when the displayed hit is greater than the average of two random numbers from 0 to 99, rounded down; each number scales a 16-bit `NextRN()` by 100/65,536.	Code
	Computed from the code, taking the two numbers as independent and evenly spread, a displayed hit $h$ connects $h (2 h + 1)$ times in 10,000 up to 50 and $10,000 - (100 - h) (199 - 2 h)$ times above it, so a displayed 80 hits 92.2% of the time, 20 hits 8.2%, and 50 hits 50.5%.	Code
	In the North American build, a unit's hit is twice its skill, plus its weapon's hit, half its luck, and the weapon triangle's bonus; its avoid is twice its attack speed plus its terrain's avoid and its luck; the hit shown and rolled is the attacker's hit less the defender's avoid, held within 0–100.	Code
Permadeath	In the North American build, a player unit whose HP reaches 0 in combat is flagged dead and hidden rather than erased, unless it is a phantom, which is erased; the cleanup between chapters keeps the flag, clearing it only for a class with the supply attribute.	Code
Weapon triangle	In the North American build, the weapon triangle gives 15 hit and 1 damage to the side whose weapon type has the edge and takes the same from the other; swords beat axes, axes lances, and lances swords, and anima beats light, light dark, and dark anima.	Code
Weapon triangle	In the North American build, a reaver weapon on one side only reverses the weapon triangle and doubles it, to 30 hit and 2 damage.	Code

References

^In the North American build, an attack hits when the displayed hit is greater than the average of two random numbers from 0 to 99, rounded down; each number scales a 16-bit NextRN() by 100/65,536.Codefireemblem8u

How we know

68int NextRN_100(void) {
69    // take the next rn (range 0-0xFFFF) and convert it to a range 0-99 value
70    return NextRN() * 100 / 0x10000;

src/rng.c lines 68–70 at 04d1edb · upstream ↗

89s8 Roll2RN(int threshold) {
90    int average = (NextRN_100() + NextRN_100()) / 2;
⋮
92    return (threshold > average);

src/rng.c lines 89–93 at 04d1edb · upstream ↗

1007    if (!(gBattleHitIterator->attributes & BATTLE_HIT_ATTR_SURESHOT)) {
1008        if (!BattleRoll2RN(gBattleStats.hitRate, TRUE)) {
1009            gBattleHitIterator->attributes |= BATTLE_HIT_ATTR_MISS;

src/bmbattle.c lines 1007–1011 at 04d1edb · upstream ↗

879void BattleUpdateBattleStats(struct BattleUnit* attacker, struct BattleUnit* defender) {
⋮
882    gBattleStats.hitRate = attacker->battleEffectiveHitRate;

src/bmbattle.c lines 879–882 at 04d1edb · upstream ↗

260    PutNumberTwoChr(gUiTmScratchA + 0xA8 + 0x40, 2, gBattleActor.battleEffectiveHitRate);

src/bksel.c line 260 at 04d1edb · upstream ↗

Checked against the evidence by its author, an AI model, 2026-10-21.

Checked by a second AI model, 2026-10-21.

In the claim ledger

^Computed from the code, taking the two numbers as independent and evenly spread, a displayed hit $h$ connects $h (2 h + 1)$ times in 10,000 up to 50 and $10,000 - (100 - h) (199 - 2 h)$ times above it, so a displayed 80 hits 92.2% of the time, 20 hits 8.2%, and 50 hits 50.5%.Codefireemblem8urevised
How we know
```
89s8 Roll2RN(int threshold) {
90    int average = (NextRN_100() + NextRN_100()) / 2;
⋮
92    return (threshold > average);
```
src/rng.c lines 89–93 at 04d1edb · upstream ↗
Checked against the evidence by its author, an AI model, 2026-10-21.
Revised after a check by a second AI model, 2026-10-21.
In the claim ledger

^In the North American build, a unit's crit is its weapon's crit plus half its skill, plus 15 for classes with a crit bonus; the crit shown and rolled is that less the defender's luck, at least 0, and one random number from 0 to 99 below it triples the hit's damage.Codefireemblem8u

How we know

589    bu->battleCritRate = GetItemCrit(bu->weapon) + (bu->unit.skl / 2);
⋮
591    if (UNIT_CATTRIBUTES(&bu->unit) & CA_CRITBONUS)
592        bu->battleCritRate += 15;
⋮
596    bu->battleDodgeRate = bu->unit.lck;

src/bmbattle.c lines 588–597 at 04d1edb · upstream ↗

612    attacker->battleEffectiveCritRate = attacker->battleCritRate - defender->battleDodgeRate;
⋮
615        attacker->battleEffectiveCritRate = 0;
⋮
617    if (attacker->battleEffectiveCritRate < 0)
618        attacker->battleEffectiveCritRate = 0;

src/bmbattle.c lines 612–618 at 04d1edb · upstream ↗

85s8 Roll1RN(int threshold) {
86    return (threshold > NextRN_100());

src/rng.c lines 85–87 at 04d1edb · upstream ↗

1030    if (BattleRoll1RN(gBattleStats.critRate, FALSE) == TRUE) {
⋮
1038            gBattleHitIterator->attributes = gBattleHitIterator->attributes | BATTLE_HIT_ATTR_CRIT;
1039            gBattleStats.damage = gBattleStats.damage * 3;

src/bmbattle.c lines 1030–1039 at 04d1edb · upstream ↗

883    gBattleStats.critRate = attacker->battleEffectiveCritRate;

src/bmbattle.c line 883 at 04d1edb · upstream ↗

243    critRate = gBattleActor.battleEffectiveCritRate;

src/bksel.c line 243 at 04d1edb · upstream ↗

Checked against the evidence by its author, an AI model, 2026-10-21.

Checked by a second AI model, 2026-10-21.

In the claim ledger

^In the North American build, a level-up rolls each of seven stats on the character's own growth rate, with one random number from 0 to 99; each full 100 of a rate is a sure point, and if no stat rises, the game rerolls the stats in order up to twice, stopping at the first that does.Codefireemblem8u

How we know

1227int GetStatIncrease(int growth) {
⋮
1230    while (growth > 100) {
1231        result++;
1232        growth -= 100;
⋮
1235    if (Roll1RN(growth))
1236        result++;

src/bmbattle.c lines 1227–1238 at 04d1edb · upstream ↗

1275        growthBonus = (bu->unit.state & US_GROWTH_BOOST) ? 5: 0;
⋮
1278        bu->changeHP  = GetStatIncrease(bu->unit.pCharacterData->growthHP + growthBonus);
⋮
1281        bu->changePow = GetStatIncrease(bu->unit.pCharacterData->growthPow + growthBonus);

src/bmbattle.c lines 1275–1281 at 04d1edb · upstream ↗

1299        if (statGainTotal == 0) {
1300            for (statGainTotal = 0; statGainTotal < 2; ++statGainTotal) {
1301                bu->changeHP = GetStatIncrease(bu->unit.pCharacterData->growthHP);
⋮
1303                if (bu->changeHP)
1304                    break;

src/bmbattle.c lines 1299–1304 at 04d1edb · upstream ↗

Checked against the evidence by its author, an AI model, 2026-10-21.

Checked by a second AI model, 2026-10-21.

In the claim ledger

Sources

Code

FireEmblemUniverse contributors. 2026. “fireemblem8u: decompilation of Fire Emblem: The Sacred Stones.” FireEmblemUniverse. Commit 04d1edb. FireEmblemUniverse/fireemblem8u @ 04d1edb · licence, all uses

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