The summary.
THE PLAYER MUST ALWAYS BE ABLE TO ANSWER WHY SOMETHING HAPPENED
Telegraph attacks, show probabilities, and never let randomness decide outcomes the player cannot influence. Damage from off screen and unwarned attacks feel arbitrary rather than deserved.
LONGER IS NOT HARDER
Raising health totals makes encounters long, not difficult.
WITHOUT SINKS, CURRENCY ACCUMULATES UNTIL IT IS MEANINGLESS
Model income against costs before building. Balancing an economy by intuition produces one that breaks within hours.
STABLE IDENTIFIERS, DISPLAY NAMES SEPARATE
Renaming an item otherwise breaks every save and every reference to it.
NEVER AUTOSAVE INTO AN UNWINNABLE STATE
It can end a playthrough permanently, and it is among the most damaging defects a game can ship.
Repeating already-solved content after failure is the primary source of frustration.
COYOTE TIME AND INPUT BUFFERING EXIST BECAUSE PERCEPTION DIFFERS FROM SIMULATION
Matching the player's perception is what makes movement feel fair.
A DOMINANT STRATEGY REMOVES THE DECISIONS YOUR SYSTEMS EXISTED TO CREATE
Strengthen the unused rather than weakening everything — it preserves the feeling of power.
