By name: traversal-system description: >- Architecture blueprint for traversal above the character controller: traversability markup, surface probing, volumes, anchors, climb/glide/swim, grapple, parkour, wall-run, web-swinging, mantle/vault traces, motion warping, IK, mounts, vehicles, stamina, networking, readability, and design constraints. Use when designing climbing, parkour, gliding, swimming, mounts, vehicles, grappling, traversal progression, or when players escape bounds, probes fail, automation overrides intent, or traversal trivializes the world.
Traversal System
Build the traversal layer of an open-world or action game — the system above
the character controller (character-controller owns the movement states, stamina
rates, and the mantle cascade basics; this skill owns the world data, the verb
catalog, the technical implementation, mounts/vehicles, and the economy).
References: BotW/TotK and Genshin (the systemic-climbing school), broadened with
the parkour/momentum tradition (Mirror's Edge, Titanfall 2, Spider-Man) and the
mount/vehicle canon (RDR2, Elden Ring, Death Stranding).
The architecture rule
Traversal is a dialogue between world markup and player verbs.
WORLD SIDE climbable-by-default markup (BotW) OR authored+telegraphed routes
(parkour); runtime shape-sweep probing; volumes (water/updraft/
current/ladder); anchors; readability cues
VERB SIDE composable modules (the Capabilities pattern); each declares its
required world data, controller services, costs, animation/IK,
and interrupt contract; granted by progression/equipment/region
IMPLEMENTATION mantle/vault trace cascade → motion-warp → IK; surface probing
at scale; wall-run/grapple physics; custom movement modes + net
MOUNTS/VEHICLES bonding, flying trivialization, build-your-own, multi-crew
ECONOMY stamina (spend/deplete) OR momentum (accumulate/protect) as the
governor; the anti-trivialization valves
Verbs emit intents into the controller pipeline — never write velocity or position.
The two economies (the headline contrast)
- Systemic-climbing (BotW/Genshin): stamina is a resource you spend and deplete; an unaffordable cliff is impassable for now; the wall is economic, not an invisible barrier. Climb-everything removes the readability problem (every surface is an affordance) at the cost of route-reading skill.
- Parkour/momentum (Mirror's Edge/Titanfall 2): speed is a resource you accumulate and protect; momentum is the "fuel" (loss felt as a slowdown, not a bar); geometry is authored, telegraphed, and exclusive, making route-reading itself the skill. The recurring fault line is automation ↔ expression — AC's "press up to win" backlash vs Mirror's Edge's losable manual inputs.
These reward opposite player behaviors — pick a school deliberately, or blend knowingly (Dying Light's "Natural Movement" is climb-anything in first-person, at the cost of breaking level-design smoke-and-mirrors).
Reference map
| File | Covers |
|---|---|
| world-data.md | Climbable-by-default markup (the BotW inversion), runtime surface probing, volumes, anchors, guidance without walls, AND readability/telegraphing (Runner Vision, the yellow=climbable convention, the freedom-vs-authored-route tension) |
| verbs.md | The verb declaration contract, climbing/glide/swim/grapple deep dives, AND the parkour/momentum verbs (wall-run, free-running, web-swinging, the automation-vs-expression axis, coyote-time/buffering for flow) |
| implementation.md | Mantle/vault/climb detection (the trace cascade, GASP), motion warping, procedural IK, surface probing at scale, wall-run and grapple physics, custom movement modes and network prediction |
| mounts-vehicles.md | Mount handling and bonding (RDR2, Agro, the indirect-control lesson), mounts as progression/collection, the flying-mount trivialization debate (Elden Ring Torrent as the counter-model), vehicles and build-your-own, multi-crew sailing, traversal-as-loop |
| economy.md | Stamina as the governor (upgrade curves, consumables, regional pools), the climb→glide loop, and the design valves against endgame trivialization |
| pitfalls.md | 15 failure modes (symptom → cause → prevention) with debugging order and ship checklist |
Build order (4 shippable tiers)
Tier 1 — Climb/parkour the world
- [ ] Surface markup channel (climbable-by-default + authored no-climb) with a
DEBUG VISUALIZATION, OR authored+telegraphed parkour routes
- [ ] Surface prober: shape sweep + refinement → stable climb frame; hysteresis
- [ ] Climb/parkour verb over the controller HSM
- [ ] Mantle/vault: the GDC windows + the trace cascade
Tier 2 — The air/momentum loop
- [ ] Glide + dive (stamina school) OR wall-run + momentum chaining (parkour)
- [ ] Verb transition buffering (coyote-time, jump buffer, refractory)
- [ ] Terminal stamina policy / momentum-loss feedback
- [ ] Per-verb camera presets
Tier 3 — Water, anchors, regions, grapple
- [ ] Swim/dive; grapple/swing through the SAME collide-and-slide solver
- [ ] Regional verb granting; IK visual layer (warp first, IK polishes)
Tier 4 — Mounts, vehicles, polish
- [ ] Mount as controller-swap (validated dismount); flying valve decided
- [ ] Vehicles / build-your-own if used; multi-crew if co-op
- [ ] Assist ladder in settings; streaming + save guards
Key numbers (starting points — the strongest anchors)
| Parameter | Value | Anchor |
|---|---|---|
| Vault / mantle windows | 0.4–0.8× / 0.8–1.4× character height; detect ≤2.5× bbox | GDC 2012 (Splash Damage) |
| Coyote time / jump buffer | ~80–150 ms (often coded 0.1 s) — flow enablers | tutorials (approx) |
| Titanfall 2 momentum | acrobatic chaining |
dev (ceiling) |
| BotW wheel economics | ~20–25 s climb / ~40–45 s glide per wheel; 4 orbs × 10 vessels | community |
| RDR2 horse bonding | 4 bond levels; each grants a maneuver + stat bump | community wiki |
| Elden Ring Torrent | double-jump (1×, redirectable) + Spiritsprings negate fall damage | wiki |
| WoW mount speed | +100% ground / +220–420% fly; Skyriding momentum-based | official |
| GASP detection | trace cascade → Chooser Table → Motion Warping (UE5.4+) | Epic |
Full sourced tables (with flagged "do-not-invent" gaps) in each reference file.
Engine mapping (summary)
| Generic block | Unity 6 | UE5 (5.4+) |
|---|---|---|
| Movement base | Kinematic Character Controller + custom states | CMC MOVE_Custom + PhysCustom; Mover plugin (experimental) |
| Mantle detection | CapsuleCast/SphereCast cascade |
trace cascade → GASP TryTraversalAction |
| Align anim→geometry | Animator.MatchTarget + Animation Rigging |
Motion Warping (AddOrUpdateWarpTarget*, Skew Warp) |
| Limb IK | Animation Rigging TwoBoneIKConstraint |
Control Rig FBIK, Foot Placement |
| Wall-run/grapple | custom state + Verlet/distance constraint | MOVE_Custom + Verlet; Cable Component for rope |
| Mounts | controller-swap (disable rider wholesale) | possession swap vs attached pawn |
Full detail in implementation.md.
Related skills
character-controller— the movement HSM, stamina rates, mantle cascade, intent pipeline this layer drives.world-time-weather— weather as the traversal valve (rain slip, updrafts).teleport-map-unlock— the teleport-vs-traversal tension; earned-only unlocks.open-world-streaming— verbs check world-data residency; traversal speed defines streaming radii.camera-system— per-verb camera presets.save-persistence— mid-traversal restore policies.game-architecture-patterns— Component (verbs), Type Object (surface profiles), Event Queue (volume intents) theory.