the biggest mistake in pokemon’s catch rate formula.
in 1996, pokemon red and blue introduced a clear ball progression: poke ball, great ball, ultra ball. players assumed the ultra ball was always the best option short of a master ball.
but gen’s 1 rate had a secret. the catch formula runs in two stages. first, the game rolls a random number whose range depends on the ball:
- poke ball: 0–255
- great ball: 0–200
- ultra ball: 0–150
secondly, it computes an hp factor:
f = floor( (max hp × 255 × 4) / (current hp × ball modifier) )
the catch is in the modifiers. the great ball uses 8, while the ultra ball and poke ball both use 12. a smaller divisor produces a larger hp factor, which gives the great ball a stronger overall catch chance than the ultra ball whenever the target still has plenty of health, roughly above 50% hp.
so the "upgrade" was really a downgrade in many early and mid game situations. the ultra ball only pulled ahead consistently once the target was very low on hp.
the likely cause is that game freak adjusted the great ball's hp modifier, probably hoping to make it stronger at high health, but never reworked the rest of the formula or explained the change.
Kirby and the Forgotten Land had some of the most beautiful concept art that the team at HAL Laboratory has created for the franchise. If you haven’t seen these early illustrations of the game’s world, check them all out! ✨ (1/3)