Lie About Probability for Consistency or Vibes

Some games lie about the chance that something will occur. This might make the randomness feel more consistent to the player or limit frustration for those instances where the unlikely occurs.

In most Fire Emblem games, a unit’s hit chance will be displayed before confirming the attack. This number is a lie, or at least a simplification to the point of lying.

While the game might display a 90% chance to hit, it rolls two numbers and uses the mean to determine the result. When the game displays a 90% chance to hit, it is actually about a 98% chance to hit. This works both ways: an attack that has a nominal 30% chance to hit actually has about an 18% chance to hit.

This makes attacks feel more consistent: if you appear likely to hit, you probably will. It also means luck (as in the random generator) has a deemphasized effect compared to unit stats.

A more subtle variant appears in Advance Wars 2. The damage value displayed before attacking is usually the minimum amount of damage the attack will do; it can do 0–9% more damage.11 Nell and Flak also have a higher base good luck, which increases when they use their CO and Super CO powers. Sonja and Flak also have bad luck, which can reduce the real damage below the preview. Thus, a preview of 95% damage has a chance of destroying a unit at full health.

1 Nell and Flak also have a higher base good luck, which increases when they use their CO and Super CO powers. Sonja and Flak also have bad luck, which can reduce the real damage below the preview.
See Also
Roll Multiple Times to Weight the Middle.
Fire Emblem True Hit (external link)
Advance Wars Luck (external link)