Non-human species' physical constraints cascade into every worldbuilding detail — and no tool helps authors track the ripple effects

Summary

Fantasy writers introducing non-human races (centaurs, merfolk, winged peoples, giants) face a hidden consistency trap: a single physiological fact — a horse-sized body can't climb stairs or ladders, can't fit through human doorways — logically forces changes across architecture, inn layouts, furniture, social customs (washing hooves before entering a home), settlement design (wide streets, single-story longhouses), transport, and even plot structure (the centaur co-protagonist must be written out of the tower-climb). Authors describe this as a constant, exhausting negotiation between creative opportunity and 'internal limitations,' and every new detail they invent creates downstream obligations they must remember across many connected stories. Existing worldbuilding tools (Obsidian templates, World Anvil, Campfire, generic note apps) store entries but do not model derived constraints: they cannot flag that a newly written two-story tavern contradicts an established species trait, cannot generate the cultural/architectural consequences of a body plan, and cannot surface the second-order implications an author hasn't thought of. The result is exactly the scattered, inconsistent canon the author is trying to avoid — contradictions discovered late, retcons, and stalled inspiration because the author must mentally simulate physics and culture for every scene. This is unsolved, high-friction, and squarely in the wheelhouse of writers and TTRPG GMs who would pay for a codex that understands species constraints and automatically checks and propagates their consequences.