diff --git a/games/age-of-dwarves/guide/src/simulation/simulation.worker.ts b/games/age-of-dwarves/guide/src/simulation/simulation.worker.ts
index d5df167f..77933e4d 100644
--- a/games/age-of-dwarves/guide/src/simulation/simulation.worker.ts
+++ b/games/age-of-dwarves/guide/src/simulation/simulation.worker.ts
@@ -8,6 +8,8 @@ import type {
   WorkerResponse,
   FramePayload,
   EasterEggSeed,
+  EventCatalog,
+  CrossTriggers,
 } from '@magic-civ/engine-ts'
 import {
   SCENARIOS,
@@ -18,13 +20,13 @@ import {
   STARTING_ATMOSPHERES,
   deriveSubstrates,
   classifyBiome,
-} from '@magic-civ/engine-ts'
-import {
   WasmClimatePhysics,
   WasmEcologyPhysics,
   WasmGrid,
   WasmMapGenerator,
-} from '@magic-civ/physics-rs'
+  EventEvaluator,
+  DEFAULT_DT,
+} from '@magic-civ/engine-ts'
 
 // ---------------------------------------------------------------------------
 // Worker-internal scenario state
@@ -40,10 +42,12 @@ interface ScenarioState {
   wasmGrid: WasmGrid
   physics: WasmClimatePhysics
   ecology: WasmEcologyPhysics | null
+  eventEvaluator: EventEvaluator | null
   cursorScenarioTurn: number
   totalScenarioTurns: number
   worldSeed: number
   isVolcanicWinter: boolean
+  dt: number
 }
 
 const CHUNK_SIZE = 5
@@ -72,9 +76,10 @@ function wasmPhysicsStep(
   wasmGrid: WasmGrid,
   turn: number,
   seed: number,
+  dt: number,
 ): void {
-  physics.processStep(wasmGrid, turn, seed)
-  if (ecology) ecology.processStep(wasmGrid)
+  physics.processStep(wasmGrid, turn, seed, dt)
+  if (ecology) ecology.processStep(wasmGrid, dt)
   physics.stepAtmosphericChemistry(wasmGrid)
 }
 
@@ -144,14 +149,29 @@ function stepOneTurn(state: ScenarioState, scenarioTurn: number, specJson: strin
     state.wasmGrid.free()
     state.wasmGrid = jsGridToWasm(state.grid)
   }
-  wasmPhysicsStep(state.physics, state.ecology, state.wasmGrid, absTurn, state.worldSeed)
+  wasmPhysicsStep(state.physics, state.ecology, state.wasmGrid, absTurn, state.worldSeed, state.dt)
   // Compute stats in Rust — avoids full 960-tile JSON deserialization every turn.
   const prevStats = state.stats.length > 0 ? state.stats[state.stats.length - 1] : undefined
   const stats: TurnStats = JSON.parse(
     state.wasmGrid.computeStatsJson(prevStats?.avg_temp ?? 0.5, prevStats?.avg_moisture ?? 0.5)
   )
   state.cursorScenarioTurn = scenarioTurn + 1
-  return { stats, events: [] }
+
+  // Fire stochastic events — only deserialize JS grid when events would fire or
+  // there are active multi-turn effects already running.
+  let events: EcologicalEvent[] = []
+  const evaluator = state.eventEvaluator
+  if (evaluator !== null && (evaluator.checkWillFire(absTurn, state.dt) || evaluator.hasActiveEffects())) {
+    state.grid = wasmGridToJs(state.wasmGrid)
+    events = evaluator.evaluateTurn(state.grid, absTurn, state.dt)
+    if (events.length > 0) {
+      // Sync any event-driven grid mutations back to WASM
+      state.wasmGrid.free()
+      state.wasmGrid = jsGridToWasm(state.grid)
+    }
+  }
+
+  return { stats, events }
 }
 
 function addCheckpoint(state: ScenarioState, turn: number): void {
@@ -187,7 +207,7 @@ function seekToTurn(state: ScenarioState, targetSt: number): void {
         state.wasmGrid.free()
         state.wasmGrid = jsGridToWasm(state.grid)
       }
-      wasmPhysicsStep(state.physics, state.ecology, state.wasmGrid, absTurn, state.worldSeed)
+      wasmPhysicsStep(state.physics, state.ecology, state.wasmGrid, absTurn, state.worldSeed, state.dt)
     }
     state.grid = wasmGridToJs(state.wasmGrid)
     state.cursorScenarioTurn = targetSt
@@ -219,7 +239,7 @@ function seekToTurn(state: ScenarioState, targetSt: number): void {
       state.wasmGrid.free()
       state.wasmGrid = jsGridToWasm(state.grid)
     }
-    wasmPhysicsStep(state.physics, state.ecology, state.wasmGrid, absTurn, state.worldSeed)
+    wasmPhysicsStep(state.physics, state.ecology, state.wasmGrid, absTurn, state.worldSeed, state.dt)
   }
   state.grid = wasmGridToJs(state.wasmGrid)
   state.cursorScenarioTurn = targetSt
@@ -263,7 +283,7 @@ async function prebufferFrames(state: ScenarioState, scenarioId: string, frameCo
             tmpWasmGrid.free()
             tmpWasmGrid = jsGridToWasm(tmpGrid)
           }
-          wasmPhysicsStep(tmpPhysics, tmpEcology, tmpWasmGrid, absTurn, state.worldSeed)
+          wasmPhysicsStep(tmpPhysics, tmpEcology, tmpWasmGrid, absTurn, state.worldSeed, state.dt)
         }
 
         // Use writeFrameBuffers for the texture data (hot path)
@@ -370,6 +390,7 @@ async function handleRun(scenarioId: string, turns: number, prebufferFrameCount:
   const worldAge = config.worldAge
   const totalAbsTurns = worldAge + turns
   const isVolcanicWinter = config.id === 'volcanic_winter'
+  const dt = config.dt ?? DEFAULT_DT
 
   // Planet-specific params override earth defaults when available
   const planet = config.planet ?? 'earth'
@@ -436,7 +457,7 @@ async function handleRun(scenarioId: string, turns: number, prebufferFrameCount:
         if (geoEcology) geoEcology.free()
         return
       }
-      wasmPhysicsStep(geoPhysics, geoEcology, geoWasmGrid, turn, seed)
+      wasmPhysicsStep(geoPhysics, geoEcology, geoWasmGrid, turn, seed, dt)
 
       if (turn % CHUNK_SIZE === 0) {
         post({ type: 'progress', scenarioId, turn, total: totalAbsTurns, phase: 'geology' })
@@ -468,15 +489,29 @@ async function handleRun(scenarioId: string, turns: number, prebufferFrameCount:
   const physics = new WasmClimatePhysics(effectiveParamsJson, terrainJson, baseSpecJson)
   const ecology = config.abioticWorld ? null : new WasmEcologyPhysics()
   const wasmGrid = jsGridToWasm(grid)
+
+  // Build event evaluator from ecological_events catalog loaded at init
+  const ecologicalEvents = baseSpec.ecological_events as Record<string, unknown> | undefined
+  let eventEvaluator: EventEvaluator | null = null
+  if (ecologicalEvents) {
+    const { cross_triggers: crossTriggersRaw, ...eventCategories } = ecologicalEvents
+    eventEvaluator = new EventEvaluator(
+      eventCategories as EventCatalog,
+      (crossTriggersRaw ?? {}) as CrossTriggers,
+      seed,
+    )
+  }
+
   const state: ScenarioState = {
     config, grid, wasmGrid, physics,
-    ecology,
+    ecology, eventEvaluator,
     stats: [], events: [], timings: [],
     checkpoints: new Map(),
     cursorScenarioTurn: 0,
     totalScenarioTurns: turns,
     worldSeed: seed,
     isVolcanicWinter,
+    dt,
   }
 
   addCheckpoint(state, 0)
@@ -592,7 +627,7 @@ function handleFrame(scenarioId: string, turn: number, lookahead: number): void
         tmpWasmGrid.free()
         tmpWasmGrid = jsGridToWasm(tmpGrid)
       }
-      wasmPhysicsStep(tmpPhysics, tmpEcology, tmpWasmGrid, absTurn, state.worldSeed)
+      wasmPhysicsStep(tmpPhysics, tmpEcology, tmpWasmGrid, absTurn, state.worldSeed, state.dt)
     }
 
     // Use writeFrameBuffers for texture data