Series

Mother

3 games, 1989–2006.

Games

Mechanics

Mechanic	EarthBound Beginnings 1989	EarthBound 1994
Critical hit	Stat against stat	From a stat
Damage formula	Attack minus defense	Attack minus defense
Fleeing	Fixed chance	Speed gap, rising by turn
Hit chance	Dodge, stat against stat	Miss, then a stat dodge
Instant win		Guaranteed win
Random encounter	By area
Rolling HP meter	At once	Rolling
Turn order	Stat plus a roll	Stat plus a roll
Visible encounter		Touch and facing

A marked cell changed from the game before. “Uses” means the game has the mechanic, with no variant recorded yet.

Every claim, by mechanic and game

Concept	EarthBound Beginnings 1989	EarthBound 1994
Critical hit	In EarthBound Beginnings (English build), a plain attack is a "SMAAAASH!!" when a random byte is below max(0, ⌊(256 + attacker's Fight − target's Fight) ÷ 2⌋ − 102), about 26 in 256 at equal Fight. It is checked before the dodge roll, so it can't be dodged, and it deals the attacker's Offense, ignoring Defense. There is no SMAAAASH during the invincibility scripts, while the party fires the tank gun instead, or, 1 time in 2, from a blinded attacker. Code	In EarthBound (US release), a bash is a "SMAAAASH!!" with a chance of about the attacker's Guts in 500, with a party member's Guts counted as at least 25 (about 1 in 20). It is rolled after the miss check and before the dodge, so it can't be dodged, and deals 4 × Offense − Defense with no random spread. Code EarthBound (US release) keeps EarthBound Beginnings' order of a plain attack, with the "SMAAAASH!!" rolled before the dodge so it can't be dodged, but changes the numbers: the chance comes from the attacker's Guts alone (about Guts in 500) instead of Fight against Fight; the SMAAAASH deals 4 × Offense − Defense instead of the full Offense; a normal hit deals 2 × Offense − Defense instead of Offense − Defense ÷ 2; and the dodge comes from Speed instead of Fight. Code
Damage formula	In EarthBound Beginnings (the English build that the 2015 Virtual Console release uses), a shared routine adds random spread to a value: it moves the value by a weight in percent drawn from a 128-entry table by a random byte, up or down at even odds. The weights run from 0 to 24, and 92 of the 128 entries are 10 or less, so most rolls move the value by a few percent. Damage and the turn-order Speed roll both use it. Code In EarthBound Beginnings (English build), a normal attack deals the attacker's Offense less half the target's Defense; when the Offense is below the Defense it deals (3 × Offense − Defense) ÷ 4 instead, at least 1. The damage routine then applies the ±0–24% spread, halves the result for a shielded or guarding target, and deals at least 1. Code	In EarthBound (US release), a bash deals 2 × the attacker's Offense − the target's Defense, moved up or down by up to 25%, and at least 1. The spread draws two random bytes and keeps the one nearer 128; its distance d from 128 moves the damage by d/512 of it, down when the byte is under 128 and up when over, so small changes are the most common. Code
Fleeing	In EarthBound Beginnings (English build), running away works 1 time in 2 (the top bit of a random byte), with no stat in it, and never in a battle an event started. Code	In EarthBound (US release), running away never works against a boss. Otherwise it works on the first turn of a battle the party started with the first strike, or when no enemy can act; else it works with a chance of about (10 × the turn number + the fastest party member's Speed − the fastest able enemy's Speed) in 100, and never when that is below 0. Code
Hit chance	In EarthBound Beginnings (English build), the target of a plain attack dodges when a random byte is at most max(0, ⌊(256 + target's Fight − attacker's Fight) ÷ 2⌋ − 102), 27 in 256 at equal Fight; a paralyzed, sleeping, or petrified target can't dodge. The attacker has no accuracy stat of its own. Code	In EarthBound (US release), a bash first misses at the attacker's miss rate in 16: for a party member its weapon's, or 1 with no weapon, plus 8 while crying or nauseous; for an enemy its own. Then the target dodges with a chance of about (2 × target's Speed − attacker's Speed) in 500, never when that is 0 or less, nor while the target is paralyzed, asleep, immobilized, or solidified. Code
Instant win		In EarthBound (US release), a battle the party can't lose is won without being fought. The check fails if the enemies struck first, or if there are more enemies than able party members among the four main characters (unconscious, diamondized, paralyzed, nauseous, poisoned, sunstroked, cold, mushroomized, and possessed ones don't count). In an even start, the four's lowest Speed must be at least every enemy's Speed, and twice their lowest Offense at least each enemy's HP plus Defense. When the party struck first, it sorts the able members by Offense and the enemies by HP, both highest first, and plays one round in that order: each member makes one attack of 2 × Offense − Defense on the current enemy, moving on to the next enemy only when one falls (any surplus damage is lost), and the party wins if every enemy falls. Code
Random encounter	In EarthBound Beginnings (English build), each step in an area with encounters starts a fight when a random byte is below a rate from the table 32, 21, 16, 13, 10, 8, 6, 5 (in 256), indexed by the area's frequency class (1–7) plus a counter, capped at the eighth entry. The counter rises by 1 with each encounter, up to 2, so the rate drops after fights; it returns to 0 in areas without encounters and after a fade-out transition. Code
Rolling HP meter	In EarthBound Beginnings (English build), damage comes off the target's HP in one subtraction, and the target falls when it reaches 0 or below: there is no rolling meter. Code	In EarthBound (US release), damage to a party member sets a target HP, and the HP shown counts toward it over time: each call moves one party slot (picked by the frame counter's low two bits) by 1.125, 1.094, or 1.0625 HP by the text speed setting. Healing rolls at 6.25 HP per update when a fastest flag or the flip-out mode is set; damage rolls at 6.25 only in the flip-out mode. A character falls only when that rolling HP reaches 0. When the last enemy falls, each meter still rolling down stops where it is, so mortal damage that hasn't finished rolling doesn't knock anyone out. Enemies and guest characters take damage at once. Code
Turn order	In EarthBound Beginnings (English build), the next combatant to act is picked one at a time: every combatant yet to act this round rolls its Speed through the ±0–24% spread, capped at 255, and the highest goes; the rest roll again for the next pick. Code	In EarthBound (US release), every conscious combatant's initiative is rolled at the start of each turn: its Speed moved up or down by up to 50% (the 25% spread's method without the final halving), at least 1. Then the conscious combatant yet to act with the highest initiative goes next, ties going to the later slot. Code
Visible encounter		In EarthBound (US release), a battle starts when an enemy on the map touches the party, and the two's facings decide who strikes first. With the direction from the enemy to the party rounded to one of eight: the party strikes first when the enemy isn't moving toward the party (within 45°) and the leader isn't facing away from the enemy; the enemies strike first when the enemy is moving toward the party and the leader faces away; otherwise neither does. A standing enemy always gives the party the first strike. Code In EarthBound (US release), an enemy on the map turns and runs from the party when its group's run-away event flag holds the value the group names (its run_away_flag_state byte), or when the levels of the party's main characters (not guests) summed are more than 10 times the enemy's level; more than 8 times for 3 enemies in 4, and more than 6 times for 1 in 2, by a random byte each enemy gets when it spawns. Code