Rarity tiers and multiplier scaling
Most games organize loot into four main tiers: common (50% drop rate), rare (35%), epic (12%), and legendary (3%). Each tier typically has a multiplier applied to item power. A common sword deals 10 base damage, but a rare version deals 15 (1.5x), an epic 22 (2.2x), and a legendary 35 (3.5x). These multipliers are content design tools: legendary drops feel meaningful because they give a tangible power jump, not just a visual upgrade.
Drop rates are tuned so legendary items are uncommon enough to feel rewarding but common enough that casual players see one every 30-50 fights. Too rare (1% drop) and the item becomes a myth among casuals; too common (30% drop) and rarity loses meaning.
Balancing dopamine vs progression pacing
The ratio between tiers controls the game's reward curve. A game with 70% common and only 1% legendary creates a slow power progression that keeps players grinding. A game with 25% legendary and 10% rare makes gear upgrades feel constant and frenetic. The best tier-list distribution depends on session length: roguelikes compress the entire progression into 30 minutes, so they stack 30% rares, while MMOs space rewards out over thousands of hours and use stricter legendary gates.