# The Frontier Cell This is V5's open prairie. The Frontier cell is the Red Dead Redemption surface where the moment-to-moment loop is **ride, track, hunt, camp, and outrun a posse** — the genre that lives or dies on texture of a different kind than the crime sandbox: not whether a chase feels seamless, but whether a horse _answers_ when you ask it to canter, whether a slow-mo headshot lands with the right sepia weight, whether a perfect pelt rewards the patience of the right caliber and a clean kill, and whether riding from camp to town turns up a downed rider or an ambush that feels authored rather than rolled. It is V5's most deliberately _patient_ cell — fast travel exists but is gated behind discovery, because the design wants you on horseback, inside the encounter system, across five biomes. The cell ships as two GameFeature variant modules — a single-protagonist 1899 campaign (**Outlaw Trail**) and a posse open-world multiplayer surface (**Frontier Online**) — composed over a set of shared C++ mechanic cores (`V5DeadEye`, `V5HorseAI`, `V5Hunting`, `V5Honor`, `V5Squad`). The promise is the same one every cell makes: **per-genre feel from one engine.** The slow-mo that paints six targets in sepia here is the literal same `BuildSlowMoEffect` the urban cell calls "Reflex Mode" and the sci-fi cell calls "Tactical Time"; the perfect-pelt scorer is the same one the monster-hunter cell uses for trapper outfits. This page inventories what the frontier stack does on the player's side of the screen, and points at the exact Unreal C++ behind each feature. For the full mode taxonomy, roster, and the scope this slots into, start at the hub: [../V5_features.md](../V5_features.md). ## What ships, honestly **The cell's mechanics are real, compiled, and tested.** Every module named above exists under `V5/ue/Source/` with a `Public/`/`Private/` split, a `*.Build.cs`, and a `Private/Tests/` automation spec, and the linker has been through them on this box: `libUnrealEditor-V5FrontierOutlawTrail.so`, `-V5FrontierOnline.so`, `-V5DeadEye.so`, `-V5HorseAI.so`, and `-V5Hunting.so` all sit in `V5/ue/Binaries/Linux/` next to their sources, built by the `ueagent` user. The signature math is real domain-specific code — a 7,700-kcal-per-kilo body-weight integrator, a four-tier horse-bond panic-reduction curve, a weak-spot damage table, a one-shot-to-the-vitals perfect-pelt classifier — and each is pinned by UE `IMPLEMENT_SIMPLE_AUTOMATION_TEST` assertions that check _values_, not truthiness (`TestEqual("Biome area totals 125 km2", …)`, `TestEqual("Witnessed train robbery applies bounty", …, 120.0f)`). **"Cell" means a mechanic stack composed by thin variant modules.** As with the urban cell, the frame-critical verbs live in shared cores and each playable sub-ruleset is a content-and-validation module whose `Build.cs` wires the mechanics it needs — `V5FrontierOutlawTrail.Build.cs` pulls in `V5DeadEye`, `V5HorseAI`, `V5Hunting`, `V5Honor`, and `V5Squad`. The honest consequence is that the variant modules are heavier on **catalog assembly and `Require(...)` shape-gating over large authored datasets** than on novel per-frame algorithms; those live one layer down in the cores, plus a handful of frontier-only runtime libraries (`UV5_OutlawTrail_BodyWeight`, `UV5_OutlawTrail_Camp`, `UV5_OutlawTrail_Encounters`) that the module owns outright. **The data is C++ catalogs; the art is not in-tree.** Consistent with V5's 0-binary-`.uasset` accounting, the catalogs are built in code and validated hard, while the horse meshes, gang-member MetaHumans, Dead-Eye Niagara, and biome terrain those catalogs reference are _described_ by `FSoftObjectPath`, not cooked. One maturity seam is worth flagging up front: the **65 launch huntable species are procedurally seeded placeholder rows** (`outlaw.species.01`…`65`, display name "Outlaw Trail Species NN", a single generic `wildlife.family.launch` tag), while the **30 Year-1 Naturalist species are hand-authored** with real names, biomes, families, and per-species calibers (Paintbrush Fox, Glasswater Otter, Golden Bison Calf…). Both are shape-valid; only one is content-finished. Where a claim leans on the in-world runtime or on art, this page says so. ## The frontier experience — what the cell plays like ### Outlaw Trail — one gang, six camps, 125 km² `V5FrontierOutlawTrail` is the RDR surface, and its `UV5_OutlawTrail_Catalog::BuildCampaignCatalog` (`V5/ue/Source/V5FrontierOutlawTrail/Private/V5FrontierOutlawTrailSystems.cpp`) is a validator-enforced content spine. `ValidateCampaignCatalog` refuses anything but **60 main missions across 6 chapters of exactly 10 each**, **4 endings**, **22 named gang members**, **320 random encounters**, **5 biomes**, **3 Dead-Eye tiers**, **4 horse-bond tiers**, and **95 huntable species** — and it sums the five biome areas and demands they total **exactly 125.0 km²** (`FMath::IsNearlyEqual( AreaTotal, 125.0f, 0.01f)`): High Plains 31, Redwoods 28, Snowline Mountains 25, Bayou 23, Desert Mesas 18. The four endings (`BuildEndings`) are honor-banded — a High-Honor Good close, a High-Honor _Martyrdom_ (the enforcer dies redeemed), a Low-Honor close below −40, and a Cynical middle for the fence-sitters — exactly the moral-payoff shape the RDR fantasy promises. The camp is the cell's home: `BuildGangMembers` seeds 22 named outlaws (Ada Bell, Doc Mercy, Moses Flint, Vera Slate…), the first twelve flagged as mission companions, each with a daily-routine chore tag (firewatch, stables, infirmary, ledger…) and a starting relationship value. Across six chapters the camp physically relocates through the biomes — `BuildCampRelocations` moves it from Blackwater Run on the high plains, to a shady bayou hideout, a redwood hollow, a snowline refuge, and a final mesa hideout, each carrying a `threat` tag (Pinkerton patrols, winter exposure, a bounty-hunter net) and a `resource` tag (a rail spur, a riverboat dock, a border crossing). It is a moving frontier, not a static map. ### Cinematic random encounters — honor as a content dial The encounter system is the cell's signature, and it is honest about being a selection engine over a large authored set. `BuildRandomEncounters` produces **320 encounters = 8 categories × 40** — `BountyTarget`, `Ambush`, `AnimalAttack`, `LawEncounter`, `TownEvent`, `TravelEvent`, `Treasure`, `HelpNeeded` — each tagged with a biome, a chapter availability window, a cooldown, and an `EV5OTHonorEligibility` band. The runtime that surfaces them, `UV5_OutlawTrail_Encounters::GetEligibleEncounters`, filters by biome, the current chapter window, _and_ `IsEncounterEligibleForHonor`, which routes `LowOnly` encounters to low/very-low honor, `HighOnly` to high/very-high, and `Any` to everyone. That single predicate is the design's "high-honor players see more help-needed events, low-honor players see more ambushes" rule expressed as a catalog filter — your reputation is literally the dial that selects the world's content. The spec proves both ends fire (`HighHonorEncounters.Num() > 0`, `LowHonorEncounters.Num() > 0`). ## The frontier signature systems Strip the variant modules apart and the depth is in five shared-or-owned runtimes: a survival layer, the bonded horse, Dead Eye, hunting, and the honor/bounty meter — with the posse multiplayer surface sitting on top. ```mermaid flowchart TB subgraph VAR["Frontier variant modules (catalog + validate)"] OT["V5FrontierOutlawTrail
60 missions · 6 camps · 320 encounters · 125 km²"] FO["V5FrontierOnline
posse 2-7 · showdown 8 FFA · 4v4 posse-war"] end subgraph OWN["Outlaw Trail's own runtime"] BW["BodyWeight
survival: kcal/7700 → kg"] Camp["Camp upkeep
food/med/ammo → morale"] Enc["Encounters
honor-gated selection"] end subgraph SHARED["Shared mechanic cores"] DE["V5DeadEye
painted-shot slow-mo"] Horse["V5HorseAI
bond · gait · spook · permadeath"] Hunt["V5Hunting
perfect-pelt scorer"] Honor["V5Honor
meter + bounty $"] end OT --> BW & Camp & Enc OT --> DE & Horse & Hunt & Honor FO --> Horse & Honor & Net["V5Netcode · V5OnlineServices"] DE -.->|same effect, urban/scifi skins| Reuse["Reflex Mode · Tactical Time"] Hunt -.->|shared scorer| MH["Monster-Hunter cell"] Honor -->|moral compass| Bureau["Cross-Continuum Bureau"] ``` ### Survival — body weight, camp upkeep, and the saddle-inventory tether The frontier cell is the only one with a **metabolic survival layer**, and it is real physiology, not a flavour meter. `UV5_OutlawTrail_BodyWeight::ApplyMealAndTravel` starts the enforcer at **82 kg** and integrates calories: burned energy is `RidingHours × 220 + OnFootHours × 430 + 1800` base, the calorie balance accumulates, and weight changes by `CalorieBalance / 7700.0f` — **7,700 kcal per kilogram is the actual approximate energy density of body fat**, the same number a nutritionist would use. The result clamps to `[54, 125]` kg and resolves a weight class with genuine trade-offs: under **68 kg** is `underweight` (stamina ×1.05, health ×0.94 — lean and quick but fragile), over **96 kg** is `heavy` (stamina ×0.9, health ×1.06 — slower but tougher), and the band between is `average` — exactly the RDR weight simulation, expressed as one interpolation. The gang camp is the cell's resource sink. `UV5_OutlawTrail_Camp::ApplyCampDonationAndUpkeep` takes a dollar donation and converts it to stores (**food = donation/2, medicine = donation/8, ammo = donation/3**), then sums the daily needs across all 22 member rows, subtracts them, and computes per-resource _deficits_. Meeting every need lifts camp morale by `2.0 + CompletedChores × 0.25`; falling short drops it by `0.3 × total deficit`, clamped to `[0,100]`. The initial state (`BuildInitialCampUpkeep`) seeds 85 dollars, 44 food, 18 medicine, 66 ammo, 62% morale — and the spec confirms the opening camp can actually meet its first day (`Upkeep.bAllNeedsMet`). Both systems tie back to the **saddle-inventory doctrine**, the design choice that makes the horse load-bearing rather than decorative. The validated inventory split puts **12 weapon slots and 6 outfit slots on the saddle** versus only **2 weapon slots and 1 sidearm on your person** (`Catalog.InventorySplit`), and `UV5_Horse_SaddleBagInventory::BuildSaddleBagInventory` only grants access when the horse is within **50 m** (`bHorseNearby`), flipping `bCarryOverRestricted` true otherwise. A single carcass slot forces the RDR choice between the trophy on the horse's rear and the supplies it displaces. Lose the horse and you lose your arsenal — which is why the next system matters. ### Mounts — the bonded horse `V5HorseAI` is the one locomotion system in V5 with a _relationship_, and it is the frontier cell's beating heart. A horse is an `FV5HorseState` (bond tier, bond XP, stamina, health, hunger, mood, ability flags), and `UV5_Horse_Bonding` runs a four-rung ladder — **Wild → Familiar (100 XP) → Trusted (300 XP) → Bonded (600 XP)** — where each promotion unlocks real behaviours via `ApplyTierAbilities`: Trusted grants rear/side-step/drift, Bonded grants `calm-under-fire` and whistle recall. You earn that XP through the care loop in `UV5_Horse_FeedBrushTalk::ApplyCareInteraction`, which pays differentiated values — **brushing 18, feeding apples 16/oats 14/hay 12, talking 10, calming a spook 25, vet-treating 20** — while moving hunger, mood, and health on their own clamps. The bond is not cosmetic; it is wired into danger. `UV5_Horse_SpookCalm::EvaluateThreat` computes panic as threat intensity (plus 12 if there's gunfire) minus a **tier-scaled reduction of 5 / 18 / 38 / 70** — a Bonded horse simply shrugs off most of what would throw a wild one. A horse stays calm under a panic of ≤25 or if it's `bCalmUnderFire`, and only **throws its rider when panic ≥ 70 and the tier is below Trusted**. Recall obeys the same logic: `UV5_Horse_Whistle::RequestRecall` will only bring the horse from within **300 m**, refuses if a threat is near and the horse isn't bonded enough to brave it (`threat_blocked`), and otherwise returns an ETA from a tier-scaled trot of **8 / 10 / 12 m/s**. Movement itself is stamina-gated: `UV5_Horse_GaitLibrary::ApplyGait` charges a per-gait stamina cost over time and forces a slowdown to walk when the horse is spent — and a Wild, unbonded horse refuses anything faster than a walk at all. Finally, `UV5_Horse_Permadeath::ResolveDamage` honours the difficulty toggle: with permadeath enabled _and_ armed, a killed horse is gone for good (`permadeath`, saddlebag recoverable at the carcass); otherwise it clamps to 1 HP and reports `stable_recovery`. The deeper mounts dive — gaits, breeds, the wagon team — lives in the architecture companion at [../architecture/spaceship-vehicles-and-mounts.md](../architecture/spaceship-vehicles-and-mounts.md). ### Dead Eye — the painted-shot slow-mo, shared three ways `V5DeadEye` is the RDR slow-mo, and it is the cleanest proof of V5's one-engine-many-skins thesis. The gauge (`UV5_DeadEye_Gauge`) fills from `Kill (+20)`, `Headshot (+35)`, and `HonorStoryBeat (+45)` and drains while active. Three tiers gate three fantasies: **Tier 1 auto-target** (time scale 0.35, one painted mark), **Tier 2 painted-shot** (0.25, up to **6** marks via `PaintTargets`), and **Tier 3 weak-spot** (0.20, paint specific body parts through `PaintWeakSpots`). The weak-spot table is where it bites — `WeakSpotDamageMultiplier` returns **Head ×2.5, Vital ×2.0, WeaponHand ×1.35, CenterMass ×1.0** — so a late-game player painting six heads in a fifth-of-real-time bullet-ballet is doing real multiplied damage, and the catalog ties tier unlocks to story chapters (`DeadEyeTierForChapter`: Tier 2 by chapter 3, Tier 3 by chapter 5). The cross-cell reuse is literal, not rhetorical. `UV5_DeadEye_SlowMoEffect::BuildSlowMoEffect` applies a theme: `FrontierDeadEye` sets vignette 0.82, film grain 0.65, sepia 0.9, an 850 Hz audio low-pass, and a `frontier_amber` accent — the signature RDR look — while `UV5_DeadEye_ReflexMode_Urban` and `UV5_DeadEye_TacticalTime_SciFi` call the _same function_ with `UrbanReflex` (white, no sepia) and `SciFiTacticalTime` (cyan) themes. One slow-mo engine, three aesthetics, zero duplicated logic. ### Hunting, pelts, and the Naturalist journal The frontier economy is anchored to hunting, and it shares its scorer with the monster-hunter cell. `UV5_OutlawTrail_Hunting::ScorePerfectPelt` adapts a frontier species and defers to `UV5_Hunting_PerfectPeltScoring::ScorePelt` (`V5/ue/Source/V5Hunting/Private/V5HuntingSystems.cpp`), which encodes the RDR2 cleanliness rule precisely: a `Perfect` pelt requires **the correct caliber for the species**, **a clean kill** (`ShotCount == 1` into Head or Vital), **and** field dressing within `PerfectFieldDressMinutes = 15.0f`; miss any and it drops to `Good` or `Poor` with a typed reason. The trapper unlock (`EvaluateTrapperUnlock`) gates each of the 72 outfits behind a specific set of _matching_ perfect pelts plus dollars. Layered over the launch hunt is the **Year-1 Naturalist** content, which is the more finished half. `UV5_OutlawTrail_Naturalist::CatalogWildlifeInJournal` is a real collection state machine: it credits a new journal entry only if the species' `bPhotographRequiredForJournal` is satisfied (some species demand a photo before the entry completes — a fail-loud "needs a photograph" status otherwise), awards separate photo and pristine-sample credits, accumulates `TotalNaturalistXp`, and promotes the player's `NaturalistRank` across six tiers that idempotently unlock outfits. This is the hand-authored layer — 30 named species, 12 naturalist outfits, photograph gates — sitting atop the procedurally-seeded 65-species launch roster noted above. ### Honor, bounty, and the marshal response The frontier cell's reputation runs through the shared `V5Honor` substrate. `UV5_OutlawTrail_HonorBounty::ApplyHonorBeat` forwards story beats to `UV5_Honor_Meter::ApplyHonorChange` (a `[−100,100]` meter in five bands — a cruel beat drives the spec straight to `VeryLow`), while `ApplyWitnessedBounty` routes crimes to `UV5_Honor_Bounty::ApplyBountyCharge` as a dollar bounty (the spec's witnessed train robbery costs **120 dollars**). Six authored bounty offices (`BuildBountyOffices`, from Valentine to Armadillo) let you pay it down: `PayBountyAtOffice` subtracts a per-office service fee and clears the balance, with the spec confirming a partial payoff (120 → 45) and a full clear (→ 0). One honest seam: **Outlaw Trail's `Build.cs` does not depend on `V5Wanted`.** The bounty you accrue here is the `V5Honor` dollar ledger and its offices, not a star-rated heat curve. The _era-scaled marshal-and-posse response_ the design attributes to the frontier — `EV5WantedResponseEra::Frontier` spawning marshals and posse riders — lives in the shared `V5Wanted` engine that the in-world mode would invoke, and is documented alongside the Honor bridge and the Cross-Continuum Bureau XP ledger in the architecture companion at [../architecture/hunter-period-systems-and-bureau-spine.md](../architecture/hunter-period-systems-and-bureau-spine.md). Honor still feeds the cross-cell moral compass there, so being cleanly heroic or cleanly ruthless on the frontier still earns Bureau-XP toward cross-cell unlocks. ### Frontier Online — the posse surface `V5FrontierOnline` composes the horse and honor verbs into the cell's multiplayer face, and `ValidateOnlineCatalog` pins the shape of three modes: a **2–7-player dedicated-server posse open world** on the shared **500 m Frontier AOI profile** with join-in-progress; an **8-player free-for-all Frontier Showdown** on a rollback netcode tick — notably with **Dead Eye disabled** (`bDeadEyeDisabled = true`) for competitive fairness, but lasso and horse-chase enabled; and a **4v4 Posse War** on dedicated servers, best-of-five, on a 90-day ranked season cadence. Below the modes sits a regional economy (`BuildEconomyPrices`: 25 rows = 5 regions × 5 goods, each with a demand/supply scalar driving a current value) whose writes route through the shared `V5OnlineServices` balance-ledger and matchmaking contracts — the same backbone every cell rides, not bespoke endpoints. The module also authors a Year-1 **Posse War Tournament** (ranked season, maps, leaderboards) and the single-player pirate-and-Polynesian "full vision" DLC catalogs (`BuildFullVisionPirateFrontierCatalog` and its Polynesian sibling) — all real shape-checked catalogs with id-drift guards, whose geometry and live services are described, not stood up. ## Where this connects The Frontier cell is one face of a single game, and it hands off at well-defined seams: - **The other open worlds.** The Period-Drama cell shares the Honor bridge and the Bureau ledger but spends them on 1947 noir and a Mafia rank ladder — see [./period-drama-cell.md](./period-drama-cell.md) — and the Monster-Hunter cell shares the _exact_ perfect-pelt scorer and the Witcher-Sense/Eagle-Eye tracking lineage — see [./monster-hunter-cell.md](./monster-hunter-cell.md). - **The mount, in depth.** The horse's gait library, twelve breeds, wagon teams, and how it differs from the car and the spaceship are detailed in [../architecture/spaceship-vehicles-and-mounts.md](../architecture/spaceship-vehicles-and-mounts.md). - **The reputation spine.** The Honor meter, the era-scaled Wanted response, and the Cross-Continuum Bureau XP ledger this cell plugs into are in [../architecture/hunter-period-systems-and-bureau-spine.md](../architecture/hunter-period-systems-and-bureau-spine.md). - The feature hub: [../V5_features.md](../V5_features.md).