Patterns Path of Exile exemplifies

Pattern	How PoE uses it
loadout-as-budget	The 1500-node passive tree as a numeric budget (~122 points at level 100). Pathing is itself a budget.
bonus-with-drawback	Keystones — Chaos Inoculation (no chaos damage, max life = 1), Resolute Technique (always hit, never crit), and ~12 others. The genre's textbook examples.
nested-progression-graph	Three orthogonal trees: character passive, ascendancy, Atlas tree. Plus gear, gem level, and content unlocks as parallel axes.
currency-as-crafting	No gold. Every "currency" is a crafting reagent. Trade and craft compete for the same inventory.
trade-friction-as-feature	No in-game auction house, deliberately. The friction is the design.
vision-driven-iteration	Balance and content driven by GGG's stated philosophy, not by metrics. The "Vision."
community-driven-tooling	Loot filter language is shipped; the de facto filter (NeverSink) is community-maintained.
aspirational-crafting	Deterministic crafting subsystems are repeatedly nerfed; perfect items remain reachable but not built.
random-perfect-roll-economy	Affixes + tiers + influences create per-item uniqueness; perfect rolls trade for thousands of currency.
atlas-as-build	The endgame map system has its own passive tree. Players build their Atlas the same way they build a character.
meta-progression-tree	Atlas tree points come from completing maps — meta-progression decoupled from character XP.
xp-loss-penalty	10% XP loss on death in Maps. Soft permadeath cost without going full HC.
skill-as-item	Skills are gems; tradable, levelable, droppable. Skill identity floats across characters.
earned-identity-gating	Ascendancy unlock is a skill check (the Labyrinth + Izaro), not RNG.