EarthBound Beginnings/Battle Engine

Fight

Hit/miss Calculation

The attacker hits if:

(256 + AttackerFight - DefenderFight) / 2 < (RANDOM 0-255) + 102

Otherwise "[NAME] dodged swiftly." If the attacker and defender have equal Fight, the chance of hitting is approximately 90%.

Damage Calculation

The following method is used to determine attack damage:

1. Calculate base damage (round BaseDamage down):

BaseDamage (normal) = [(AttackerOffense * 3) - DefenderDefense] / 4

BaseDamage (SMAAASH!!) = AttackerOffense

2. Get random multiplier from this table. There is a 50% chance of RandMult being negative.

Odds	7.8%	7.8%	7.8%	7.8%	7.8%	7.0%	7.0%	6.3%	6.3%	5.5%	4.7%	4.7%	3.9%	3.1%	3.1%	2.3%	2.3%	1.6%	1.6%	1.6%	0.8%	0.8%	0.8%	0.8%
RandMult	0	±1	±2	±3	±4	±5	±6	±7	±8	±9	±10	±11	±13	±14	±15	±16	±17	±18	±19	±20	±21	±22	±23	±24

3. Calculate final damage (round FinalDamage down):

FinalDamage = BaseDamage * (1 ± 0.1 * RandMult)

This means that any attack can hit for 76% to 124% of its base damage.

Odds of getting a SMAAAASH!!

The chance of a SMAAAASH!! is exactly the same as the chance of missing an attack: The attacker gets a SMAAAASH!! if:

(256 + AttackerFight - DefenderFight) / 2 > (RANDOM 0-255) + 102

If the attacker and defender have equal Fight, the chance of both hitting and getting a SMAAAASH!! is approximately 9%.

PSI

PSI attacks will always hit if the defender is not PSI-protected.

Damage

PSI damage calculation currently unknown.

Healing

PSI healing calculation currently unknown.

Run away

Every non-fainted ally has a 50% chance of successfully running away, and if any one ally escapes the entire party will escape. So, the chance of successfully running away is:

1 - 0.5^{Number of non-fainted allies}

Combat data

Allies

Stored at RAM 0x0600-0x067F

• 00: Ally in party, FF if ally is in party
• 01: Status condition
  • Bit 0: Cold
  • Bit 1: Poisoned
  • Bit 2: Puzzled
  • Bit 3: Confused
  • Bit 4: Sleeping
  • Bit 5: Paralyzed
  • Bit 6: Stone
  • Bit 7: Unconscious (can be applied even when HP isn't at 0)
• 02: Unknown
• 03-04: HP
• 05-06: PP
• 07-08: Offense
• 09-0A: Defense
• 0B: Fight
• 0C: Speed
• 0D: Wisdom
• 0E: Strength
• 0F: Force
• 10-17: Unknown
• 18-19: Pointer to name
• 1A-1F: Unknown

Enemies

Stored at RAM 0x0680-0x06FF

• 00: Unknown (unused?)
• 01: Status condition
  • Bit 0: Cold
  • Bit 1: Poisoned
  • Bit 2: Puzzled
  • Bit 3: Confused
  • Bit 4: Sleeping
  • Bit 5: Paralyzed
  • Bit 6: Stone
  • Bit 7: Unconscious (can be applied even when HP isn't at 0)
• 02: Unknown
• 03-04: HP
• 05-06: PP
• 07-08: Offense
• 09-0A: Defense
• 0B: Fight
• 0C: Speed
• 0D: Wisdom
• 0E: Strength
• 0F: Force
• 10-17: Attacks
• 18-19: Pointer to enemy data
• 1A-1B: Experience
• 1C-1D: Money
• 1E: Item dropped
• 1F: Graphic tileset