# Challenge and Harrow Modifiers

A designer-facing reference for how much harder each optional run modifier makes a run: the six built-in Challenges and the twelve dials of the Artificer's Harrow, with exact effect magnitudes.

## In plain terms

Challenges are opt-in burdens a player picks before starting a run. The Artificer's Harrow is a seventh card that lets a player build a custom challenge by turning individual dials. Both are pure difficulty modifiers. Every effect makes the run harder, never easier.

Unlike almost everything else in these docs, **none of these magnitudes live in a `data/*.json` file.** They're hardcoded constants in two scripts:

- `scripts/core/ChallengeManager.gd` — the six built-in Challenges and their multipliers.
- `scripts/core/HarrowManager.gd` — the twelve Harrow dials and their base-to-worst ranges.

So retuning any number on this page is a **code change, not a data edit.** It needs a developer, and it doesn't go through the JSON validator. Treat this page as a read-only reference for the current numbers, so you can balance around them. For the code-level design detail, see the Developer page [The Artificer's Harrow](/docs/underroot/the-artificer-s-harrow).

A note on terms:

- **Multiplier (×N):** the effect scales a base value. `×0.5` halves it, `×3` triples it. Multipliers stack by multiplying together.
- **Tile:** one 32px cell of the world grid.
- **Ritual:** the in-game name for activating the Astrolabe.
- **Grace period:** the seconds at the start of a run before the Maw begins moving.

---

## The six built-in Challenges

A Challenge is either **free** (selectable the moment the system unlocks, after three Rituals) or **earned** (unlocked by meeting an endurance condition in a prior Challenge run). The unlock condition is listed for context; it has no effect on difficulty once the Challenge is active.

| Challenge | Tier | Unlock condition | What changes (exact magnitudes) |
|---|---|---|---|
| The Lone Villager | free | — | Population starts at **1**. Starting supplies cut to **10 food, 10 water, no stored buffer**. Gathering bell rings **2× slower** (`bell_interval_mult` = 2.0). Berries pick **1 at a time** (vs the usual random handful). The pond starts near dry (**10 water**) and seeps back at **0.25× rate** (`pond_regen_mult` = 0.25 — about 4/day against a 14.4/day drain). |
| Brittle World | free | — | Tool durability **×0.5** (`tool_durability_mult`). Wall HP **×0.5** (`wall_hp_mult`). |
| Eye of the Storm | earned | Survive 15 days in a Challenge run | Rain gap **×0.1** (near-constant rain) and storm gap **×0.2** (frequent storms). Storms speed the Maw **×1.75** (`maw_storm_mult`, only while a storm actually rages). Shelter fuel burns **×2** (`shelter_fuel_mult`, across 3 consumer sites). |
| The Ravenous Maw | earned | Survive 20 days, or grow a lineage of 3 | Grace period cut **360s → 60s**. Maw learns materials **×3 faster** (`maw_learning_mult`). Pressure escalation **×3 faster** (`pressure_growth_mult`). Each Ritual feeds **×2** permanent chew (`ritual_chew_mult`). |
| The Black Rot | earned | Survive 14 days with 2+ Challenges active | Every villager needs **1 strange root per day or they die**. Compensations: a starting buffer of **population × 2** strange root, plus a boosted root gold-trade (5 root for 25 gold) that only appears under this Challenge. |
| Two Fronts | earned | Survive 25 days, or perform 3 Rituals in a Challenge run | A **second Maw** grinds in from the west, with its **own outskirt wall line and breach**. Shares the escalation state of the eastern Maw. |

### How Challenge effects stack with the world

Several of these multipliers don't act alone. They multiply on top of the Maw's normal escalation:

- **Maw learning** (`×3` under Ravenous Maw) multiplies the per-material adaptation familiarity that already grows as the Maw eats.
- **Pressure escalation** (`×3` under Ravenous Maw) multiplies `balance.json → maw → pressure_growth_per_day`, which is itself compounding. A `×3` here is a very large swing.
- **Ritual chew** (`×2` under Ravenous Maw) multiplies the permanent chew increase priced by `balance.json → astrolabe`.

So a single earned Challenge can move effective difficulty far more than its headline number suggests, because it's multiplying an already-growing curve.

---

## The Artificer's Harrow — twelve dials

The Harrow is the seventh Challenge card, unlocked once a player owns all six Challenge mastery trophies. It lets a player set a **severity** `t` (from just above 0 up to 1) on any of twelve dials. `t = 0` is baseline (the dial is omitted); `t = 1` is the "worst" value in the table below. Every dial is harder-only by construction; turning one can never help the player.

Each dial's concrete value at a given severity is a linear blend between **base** and **worst**. The Hunger at `t = 0.5`, for instance, sits halfway between `×1.00` and `×4.00`, i.e. `×2.50`.

| Dial (in-game name) | Type | Base → worst | What it adjusts |
|---|---|---|---|
| The Waking (`grace`) | seconds | **360 s → 30 s** | How long the Maw sleeps before it first stirs. Lower = it wakes sooner. |
| The Hunger (`hunger`) | multiplier | **×1.00 → ×4.00** | How fast the Maw's long-term pressure grows day over day. At full turn it also raises the pressure ceiling (up to `+2` on top of the `pressure_max` of 5). |
| The Learning (`learning`) | multiplier | **×1.00 → ×3.00** | How quickly the Maw learns the taste of materials you raise against it (adaptation speed). |
| The Reckoning (`ritual_fury`) | multiplier | **×1.00 → ×2.50** | How much each Ritual feeds the Maw's permanent appetite. |
| The Frenzy (`surges`) | composite | **+0% → +100%** | Light surges come oftener (mean interval down to `×0.3`) and hit harder (boost up to `×1.667`, i.e. surge boost 1.5 → 2.5 total). |
| The Sky Turns (`sky`) | composite | **+0% → +100%** | Near-constant rain (gap to `×0.1`), frequent storms (gap to `×0.2`), and the Maw emboldened during storms (up to `×1.75`). |
| Green Iron (`tools`) | multiplier | **×1.00 → ×0.40** | Tool durability. Lower = tools fail faster. |
| Bad Mortar (`walls`) | multiplier | **×1.00 → ×0.40** | Wall HP. Lower = walls fall faster. |
| The Few (`souls`) | headcount | **47 souls → 1 soul** | How many villagers remain at the start; starting stores thin in proportion. |
| The Appetite (`appetite`) | multiplier | **×1.00 → ×2.00** | Food and water drain, both together. |
| The Cold (`cold`) | multiplier | **×1.00 → ×2.00** | How fast the shelter fires burn fuel. |
| Meager Earth (`meager`) | composite | **+0% → +100%** | The gathering bell tolls slower (up to `×2`), berry handfuls shrink toward 1, and the pond seeps back thinner (down to `×0.25`). |

### Where the Harrow and Challenges overlap

Several Harrow dials govern the same lever as a built-in Challenge (Green Iron and Brittle World both scale tool durability, for one). When a Challenge and a matching Harrow dial ride the same run, the effects **multiply**, and `ChallengeManager` applies floors and caps so a stacked config stays punishing but never degenerate (durability floored at `×0.2`, learning capped at `×6`, pressure growth capped at `×6`, and so on). A harrowed run won't crash, but it isn't promised to be balanced. Extreme dial stacks are meant to be brutal.

---

## Safe to change / handle with care

- **These numbers are script constants, not JSON.** Don't go looking for them in `data/`. Changing any value on this page is a developer task in `ChallengeManager.gd` or `HarrowManager.gd`, and the data validator won't catch it.
- **The multiplicative ones compound hardest.** Learning, pressure growth, and ritual chew all multiply an already-growing curve. A small edit to any of them moves late-run difficulty far more than the headline number implies.
- **The Harrow's floors and caps are the real safety rails.** If you retune a Challenge or dial magnitude, check that the matching floor/cap in `ChallengeManager.gd` still bounds a fully-stacked config sensibly.

## Related

- [The Levers That Matter Most](/docs/underroot/the-levers-that-matter-most)
- [Maw Threat and Escalation](/docs/underroot/maw-threat-and-escalation)
- [Survival and Supply Drain](/docs/underroot/survival-and-supply-drain)
- [The Astrolabe Consequence Curve](/docs/underroot/the-astrolabe-consequence-curve)
- [The Artificer's Harrow](/docs/underroot/the-artificer-s-harrow) (Developer — code-level detail)