Super Mario RPG's rules (Yoshifanatic's Super Mario RPG disassembly)

For the levels each character can reach, from 2 to 30 for Mario, 3 for Mallow, 7 for Geno, 9 for Bowser and 10 for Toadstool (their rows below that are zero), each level a character gains ends with a bonus the player picks from three: more Attack and Defense, more maximum HP, or more Magic Attack and Magic Defense. The amounts are a table by character and level. Defense and Magic Defense always get 1. HP, Attack and Magic Attack each repeat every three levels with amounts of their own, Mario's at levels 2 to 4 running 3, 3 and 4 HP, 1, 2 and 1 Attack, and 3, 1 and 1 Magic Attack. HP's cycle changes at level 21: Bowser's stays 1 or 3 at every level, and the others' fall to 1 to 3 (Toadstool's 3 at level 21, then 2, 1 and 1 over and over). The cursor starts on HP. Once the player picks, the screen shows the new values; A applies them and B goes back to the three choices. HP raises the maximum and fills the character's HP to it; each other stat stops at 255. Several levels from one battle each bring their own bonus, one after another. super-mario-rpg/level-up-bonus

The table has a row for every level from 2 to 30 for all five characters; Toadstool's rows hold zeros up to level 9, Bowser's to 8, Geno's to 6 and Mallow's at level 2. Left and Right are the controller's bits 0x0200 and 0x0100 in the game's copy of the SNES joypad register, A 0x0080 and B 0x8000.

An attack that runs the battle's damage step is judged as a timed hit as its damage is applied, from a record of the buttons first pressed on each frame, counted from the record's last clearing, the first frame recorded after it being frame 0 (a battle-script command clears it, and so does each judgment). Exactly one frame with a press of A, B, X or Y between the attacker's outer bounds doubles the damage if it falls between its inner bounds, and adds half otherwise; no such frame, or two or more, adds nothing, so pressing again on a later frame spoils a good press (buttons pressed together on one frame count once). The extra is shown with the damage and taken from the target's HP too. The bounds are frame counts per weapon (super-mario-rpg-tables/weapon-timing): the Hammer's inner bounds take a press 14 to 20 frames in, 7 frames (computed), and its outer bounds 8 to 38; the outer end is cut back to the number of frames recorded so far. super-mario-rpg/timed-hit

About: Super Mario RPG Action command

Value: full ×2 · partial ×1.5 · none ×1

A, B, X and Y are the bits 0x0080, 0x8000, 0x0040 and 0x4000 of the SNES joypad register the game copies. The record holds new presses, so holding a button counts once. The display update that writes it is the battle's vertical-blank routine, so an entry is a frame. A set bit 0 of 0x304E makes every judgment a full success; the battle clears it at its start, and no line found sets it.

When an enemy's attack damages a party member, the same record of first presses judges a guard, counted back from the last frame recorded before the damage is applied (frame 0). Exactly one frame with a press of A, B, X or Y between frames 62 and 1 before it, falling between 23 and 3 frames before, gives back half the damage, rounded down (the party member takes half, rounded up), if it is outside 15 to 11 frames before, and blocks all of it inside them; no such frame, two or more, or one outside 23 to 3, blocks nothing. The full block is 5 frames wide and the half block the other 16 of a 21-frame span (computed). super-mario-rpg/timed-guard

About: Super Mario RPG Timed guard

Value: span frames 62–1 before · half frames 23–3 before · full frames 15–11 before

Entry 63 is the last frame recorded and entry 0 the one 63 before it; neither is counted, so a press on those frames neither guards nor spoils a guard. The branch for a target flagged in its record (L81918-L81950) sets HP from another field instead of adding back.

An attack's damage is its power less the target's defense, at least 1 unless the power is 0, and at most 9999. An ordinary attack's power is the attacker's Attack, against the target's Defense. A special's is the caster's Magic Attack plus the special's own power, against Magic Defense, except that the four specials that restore HP (Therapy, Group Hug, HP Rain and Come Back) take no defense off (computed). An item's is its own power, with no defense taken off and no multiplier. A party member's ordinary attack first moves its Attack by a random amount: from Attack less the weapon's variance (0 if that is negative) up by 0 to twice the variance. A monster's ordinary attack has no variance; its power, a number from 0 to 7, picks a multiplier applied after the subtraction: ×1, ×1.5 (the half rounded down), ×2, ×4, ×8, ×16, ×32 or ×64. A monster's magic attack uses its Magic Attack plus that number against Magic Defense, and deals 0 when the number is 0. The halving and ×1.5 steps (super-mario-rpg/damage-status-steps) and the elements, which can make the damage 0 (super-mario-rpg/damage-elements), follow, then the 9999 cap. Three kinds of attack skip the formula (super-mario-rpg/damage-skips). A timed hit's extra comes after all of this, from the damage as applied, and has no cap of its own (super-mario-rpg/timed-hit). super-mario-rpg/damage-formula

About: Super Mario RPG Damage formula

Value: physical Attack ± weapon variance − Defense, ≥ 1 · special Magic Attack + power − Magic Defense, ≥ 1 · item item power · cap 9999

The flags are two bytes the attack's set-up fills: the first flags (0xF8) and the second flags (0xF9). The item set-up writes only the power's low byte (0xFB), and the power is read as a word with the next byte (0xFC) as its high byte, so an item deals its own power only while that byte is 0; what it holds then is not read here. The monster set-up's first flags 0x40 (from bit 5 of the attack's first byte) is a different bit from the variance's second flags 0x40. The 9999 cap compares the damage's low 16 bits as a signed number, so a value of 42,768 or more would pass it (computed). Only a monster's attack has a multiplier above ×1, and its Attack and Magic Attack are single bytes, so before the status steps it is at most (255 + 7) × 64 = 16,768, and 25,152 after the ×1.5 step (computed): under the edge against a party member. Against a monster weak to the element, doubled, it could reach 50,304 (computed); whether a monster's attack can hit a monster is not read here.

Three kinds of attack skip the damage formula (super-mario-rpg/damage-formula). One marked to deal nothing deals 0. One marked to knock out deals 9999 when it hits; it is of two kinds, and on a miss one does nothing while the other goes through the formula after all (super-mario-rpg/hit-chance). One marked to take a share deals its power in sixteenths of the target's current HP, rounded down, or, if it heals, restores that many sixteenths of the target's maximum HP, rounded down; only the 9999 cap applies after it, and it holds while the share stays under 42,768 (computed). A monster attack's knock-out bit gives the kind that does nothing on a miss; none of the party's 27 specials carries either of the other two marks (computed, super-mario-rpg-tables/specials), and which attacks do is not read here. super-mario-rpg/damage-skips

About: Super Mario RPG Damage formula

Value: knock out 9999 · share power × HP ÷ 16, rounded down

The marks are bits of the attack's flags: no damage is the first flags' 0x80; the knock-out kinds are the second flags' 0x20 (no fallback) and 0x08 (falls back to the formula on a miss); the share is the second flags' 0x10, and a heal the second flags' 0x01. The share is built in three bytes, but the cap compares only the low two, as a signed number: a share of 42,768 to 65,535 passes it uncapped, and one of 65,536 or more loses its third byte (computed). Record words 0x11 and 0x13 are the target's current and maximum HP. Before the damage routine, any attack but a heal skips a target with status bit 0x80 or boost bit 0x01; what those bits are is not read here (knocking out sets boost bit 0x80).

After the subtraction and multiplier, damage that isn't a heal is halved once (rounded down, but not below 1) if any of these holds: the attacker has the status Terrorize inflicts (bit 0x08) or status bit 0x20 (one of the two the Trueform Pin guards against); the target has status bit 0x20; the target's boost bit 0x04 is set (what sets it is not read); or the target has the boost that halves that type of attack, bit 0x40 for ordinary attacks and 0x20 for specials and items (the two bits the Bracer, the Crystalline and the Ghost Medal give). It is then raised by half once (×1.5, the half rounded down) if the target has Terrorize's status, or the attacker has the boost for its type, bit 0x10 for ordinary attacks and 0x08 for others (the two bits Geno Boost, the Energizer, the Power Blast and the Troopa Pin give). A heal skips both steps. An ordinary attack on a target with the status Sleepy Time inflicts (bit 0x02) wakes it, clearing its statuses. super-mario-rpg/damage-status-steps

About: Super Mario RPG Damage formula

Value: halve attacker feared or 0x20; target 0x20, boost 0x04, or defense boost · raise ×1.5: target feared, or attacker's attack boost

An attack with an element (Jump, Fire, Thunder or Ice) deals 0 to a target that nullifies all its elements, except that Mario's Jump-element attacks keep their damage while he wears the Jump Shoes. Otherwise a party member who resists all its elements takes half (rounded down, but not below 1), and a monster weak to all of them takes ×2. A party member's nullified and resisted elements are those of its equipment combined (the Super Suit, the Lazy Shell armor and the Safety Ring nullify all four; the Amulet and the B'tub Ring resist all four); a monster's are its own (super-mario-rpg-tables/monster-defenses). The element step runs after the status steps (super-mario-rpg/damage-formula). A party member's ordinary attack carries its equipment's attack element, which none of the 86 pieces of equipment has (computed). super-mario-rpg/damage-elements

About: Super Mario RPG Elemental weakness

Value: nullify 0 · resist ÷2 (party) · weak ×2 (monsters)

An attack with a hit rate of 100 always hits. Otherwise an attack marked to test the knock-out guard, as a monster attack's knock-out bit marks it, misses a target with that guard, which the Safety Ring, the Attack Scarf, the Jinx Belt and the Quartz Charm give from the start of a battle. Against a monster, a draw from 0 to 99 below its evade (or its magic evade, for an attack that isn't physical) is a miss; then, against any target, a draw from 0 to 99 below the hit rate is a hit. A party member's ordinary attack has a hit rate of 99, so it hits a monster with no evade 99 times in 100 (computed); against a party member only the hit rate is drawn. A miss does nothing to that target, except by the knock-out kind that falls back to the damage formula on a miss (super-mario-rpg/damage-skips). super-mario-rpg/hit-chance

About: Super Mario RPG Hit chance

Value: ordinary attack hit rate 99 · always 100

A battle begun from the field fights one of three formations from a pack, and a second value picks which of the three. A pack's four bytes hold its three formation numbers' low bytes, and bits 0, 1 and 2 of the fourth add each one's ninth bit, so a pack can name formations 0 to 511 (computed). A field routine passes the pack from a field value and the choice from a byte that another field routine saves from a field object (its byte 0x0E, saved with its byte 0x0D). A pack number of 0xFFFF fights formation 3 and sets the flag that skips the experience award. A formation's three stat bytes are loaded with it, the third setting its run chance (super-mario-rpg/run-away). super-mario-rpg/battle-formations

About: Super Mario RPG Visible encounter

Value: formations 512 · per pack 3

Running from a battle succeeds when a draw from 0 to 100 is at most the formation's run chance, 80, 50, 20 or 0 by the low two bits of its third stat byte: 81, 51 or 21 times in 101 (computed). A failed draw shows "Couldn't run!"; at 0 there is no draw and the battle shows "Can't run from this". Of the 512 formations, 12 have 80, 399 have 50, none 20, and 101 can't be run from (computed). super-mario-rpg/run-away

About: Super Mario RPG Fleeing