diff --git a/games/age-of-four/docs/CREATURE_ECOSYSTEM.md b/games/age-of-four/docs/CREATURE_ECOSYSTEM.md
index 8d48257f..9ffaeddc 100644
--- a/games/age-of-four/docs/CREATURE_ECOSYSTEM.md
+++ b/games/age-of-four/docs/CREATURE_ECOSYSTEM.md
@@ -2,6 +2,22 @@
 
 > The world is alive. Terrain is geology. Biology lives on top. Resources are populations. Everything breeds, migrates, and dies.
 
+## Detail Design Documents
+
+Each layer has a dedicated design doc in `games/age-of-dwarves/docs/design/`:
+
+| Document | Covers |
+|----------|--------|
+| [SUBSTRATE_TYPES.md](../../age-of-dwarves/docs/design/SUBSTRATE_TYPES.md) | 10 geological substrates, elevation ranges, soil types, water body identification, derivation algorithm |
+| [BIOME_CLASSIFICATION.md](../../age-of-dwarves/docs/design/BIOME_CLASSIFICATION.md) | Full classifier pseudocode (land + aquatic), ~25 biomes, 5 proof biomes, reclassification triggers, emergent succession |
+| [POPULATION_DYNAMICS.md](../../age-of-dwarves/docs/design/POPULATION_DYNAMICS.md) | Individual creature lifecycle, Lotka-Volterra with substeps, food web derivation, migration, carrying capacity, SQLite schema |
+| [SPECIES_TRAITS.md](../../age-of-dwarves/docs/design/SPECIES_TRAITS.md) | 7 trait categories, 9 constraints, quality tier derivation, spawn probability, FlavorGenerator naming, DOTA art direction |
+| [NPC_BUILDINGS.md](../../age-of-dwarves/docs/design/NPC_BUILDINGS.md) | Lair/village/ruin as map-scoped buildings, migration from tile fields, abandonment → ruin transition, creature association |
+
+This document is the architectural overview. The detail docs contain implementation-level specifications.
+
+---
+
 ## Principles
 
 1. **Geological substrate is permanent** — elevation, rock type, water depth. Set at map gen, changed only by cataclysmic events.