Game modifiers

The toggleable run mutators the game calls GameModifiers — the New Game Plus checkboxes (No boss timer, No minimap, Day only, More experience, …).

Three layers

Layer	What	Status
Definition asset	`.gamemodifierdef.ot`, loaded by the typed `oCTLibrary<GameModifierDefinition>` singleton	Additive — same dir-scan + `UsedRscList` path as enemy defs. A new def file registers automatically.
State slot	a CRC-keyed boolean per modifier in the generic entity-value store (on = active this run)	Mapped (keys below)
Behavior	what the modifier DOES is hardcoded C++ branching on the state key	Per-modifier. New behavior needs a Lua hook gated on the key, exactly like talents/items.

Key functions

GameModifierDef_RegisterAssetLoader FUN_1403257b0 — registers the *.gamemodifierdef.ot glob → library loader (label “Game modifier definition”), via the generic glob-register FUN_1404a2190. This is what proves defs are file-additive.
EntityValueRegistry_RegisterAll FUN_1401d9b70 — registers every CRC-keyed game-state value (difficulty, modifiers, multiplayer, location flags) with its label + type. Source of the key table below.
HasGameModifierStateMachine registrar FUN_140197170 — the per-run state-machine component (id 0x1b49a36c) holding which modifiers are on.
Library_GameModifierDefinition_vftable 0x141411b50.

State keys (CRC32 of the label)

Read these through the entity-value store — see Entity values.

Toggles (bool)

Modifier	Key
No boss timer	`0x1a7945fc`
Less day/night half cycle	`0x1a77d42d`
More experience (any source)	`0x1a77e2e4`
No revive token	`0x1a793d1a`
No minimap	`0x99f27eac`
One chapter	`0x1a8a3688`
Day only	`0x1a8b53b4`
Night only	`0x1a8b53bc`
Random hero at map start	`0x1ab183ab`
All same heroes	`0x1ab58780`

Difficulty / XP scalars

Value	Key
Game Difficulty	`0x18700873`
Difficulty Xp Modifier	`0x19bddb2e`
Global Xp Modifier	`0x187afd1d`
Rare Skill Chance Modifier	`0x1871c2fa`
Dream Shard Costs Modifier	`0x187310ec`
Half Cycle Count Before Boss Awakens Modifier	`0x187443de`
Camp Difficulty Modifier	`0x187aaecf`
Camp Difficulty Modifier Chance To Apply	`0x187ab36e`

Camp Difficulty Modifier + Game Difficulty are the “harder camps/bosses” levers; Global Xp Modifier / Difficulty Xp Modifier are the XP levers.

Deserialization: no bespoke reader

GameModifierDefinition / oCDtNewGamePlusModifier are not read by a hand-rolled byte reader. The ctor FUN_1401ad830 zeroes 0x238 and inits; the def goes through the engine’s generic property-reflective serializer (own property Difficulty, descriptor registrar FUN_1401fe980, field flag 0x70001; component id 0x18705119, registrar FUN_1401926c0).

Implication: a new modifier def = clone an existing .gamemodifierdef.ot, edit identity + Difficulty, register via UsedRscList. No versioned-reader wall (unlike herodefs and skills).

Lua API (shipped)

R.modifier reads modifier/difficulty state by name through the entity-value store (R.entity.value(key) → EntityValue_Get(hero+0x2f8, out, key), inline f32):

R.modifier.active("No minimap")        -- true if the toggle is on this run
R.modifier.value("Game Difficulty")    -- numeric value (or nil)
R.modifier.names()                     -- known modifier/scalar names

Read-only — it lets a mod gate custom logic on modifier state.

SDK kind (shipped)

modifier (src/rsmm/sdk/kinds/modifiers.py, engine game_modifier_cook.py) clones a vanilla def under a new id with an optional relabel + effect-key swap:

m.register("modifier", id="DoubleTrouble", base="NoBossTimer",
           name="Double Trouble", description="...",
           effect="Game Difficulty")   # reuse another modifier's behaviour key

Emits the cooked def + text-bank keys; apply registers it additively via UsedRscList. Confidence guess — the def cooks and loads, but the UI slot appearance is unproven. The cook rewrites only whole ASCII identity strings and the 4-byte behaviour key (every binary marker/count copied verbatim), so it can’t desync the opaque tail. Tests: tests/test_game_modifier_cook.py.

The “5 selected modifiers” cap

Resolved as not a spawner-data field. The select screen is the Dt Challenge Ui Controller (registrar FUN_14035f7f0), whose settings expose m_oGameModifierUiSpawner (0x1871e0aa) and m_bDisplayEmptySlots (0x1871e0ab) — which is what first suggested a data-driven slot count. The actual cap is the controller’s pad-to-5 loops plus progressive slot unlocking keyed off a profile value; lifting it above 5 means patching those loops, which is high risk and currently parked.

Open

Playtest-verify R.modifier.* reads real values, and whether a cloned modifier shows in the select screen.
Type the modifier-def tail in the codec (title/desc keys + behaviour key as first-class fields) so relabel/effect stop relying on string surgery.