diff --git a/app/ecs-systems/plant-growth.js b/app/ecs-systems/plant-growth.js
index 2d5b98f..af78aa9 100644
--- a/app/ecs-systems/plant-growth.js
+++ b/app/ecs-systems/plant-growth.js
@@ -2,6 +2,8 @@ import {System} from '@/ecs/index.js';
 
 export default class PlantGrowth extends System {
 
+  frequency = 1;
+
   static queries() {
     return {
       default: ['Plant'],
diff --git a/app/ecs-systems/water.js b/app/ecs-systems/water.js
index 20ba83e..b360bd4 100644
--- a/app/ecs-systems/water.js
+++ b/app/ecs-systems/water.js
@@ -2,6 +2,8 @@ import {System} from '@/ecs/index.js';
 
 export default class Water extends System {
 
+  frequency = 1;
+
   tick(elapsed) {
     const {Water} = this.ecs.get(1);
     for (const tile in Water.water) {
diff --git a/app/ecs/ecs.js b/app/ecs/ecs.js
index 70b4744..7725eec 100644
--- a/app/ecs/ecs.js
+++ b/app/ecs/ecs.js
@@ -344,32 +344,31 @@ export default class Ecs {
   }
 
   tick(elapsed) {
-    for (const systemName in this.Systems) {
-      if (this.Systems[systemName].active) {
-        this.Systems[systemName].tick(elapsed);
-      }
-    }
-    for (const systemName in this.Systems) {
-      if (this.Systems[systemName].active) {
-        this.Systems[systemName].finalize(elapsed);
-      }
-    }
-    this.tickDestruction();
-  }
-
-  tickDestruction() {
-    const unique = new Set();
+    const destroying = new Set();
     for (const systemName in this.Systems) {
       const System = this.Systems[systemName];
       if (System.active) {
-        for (let j = 0; j < System.destroying.length; j++) {
-          unique.add(System.destroying[j]);
+        if (System.frequency) {
+          System.elapsed += elapsed;
+          if (System.elapsed < System.frequency) {
+            continue;
+          }
+        }
+        while (!System.frequency || System.elapsed >= System.frequency) {
+          System.tick(System.frequency ? System.elapsed : elapsed);
+          for (let j = 0; j < System.destroying.length; j++) {
+            destroying.add(System.destroying[j]);
+          }
+          System.tickDestruction();
+          if (!System.frequency) {
+            break;
+          }
+          System.elapsed -= System.frequency;
         }
-        System.tickDestruction();
       }
     }
-    if (unique.size > 0) {
-      this.destroyMany(unique.values());
+    if (destroying.size > 0) {
+      this.destroyMany(destroying.values());
     }
   }
 
diff --git a/app/ecs/ecs.test.js b/app/ecs/ecs.test.js
index e51b03d..e1a84c1 100644
--- a/app/ecs/ecs.test.js
+++ b/app/ecs/ecs.test.js
@@ -209,13 +209,9 @@ test('creates entities when ticking systems', () => {
 });
 
 test('schedules entities to be deleted when ticking systems', () => {
-  let entity;
   const ecs = new Ecs({
     Systems: {
       Despawn: class extends System {
-        finalize() {
-          entity = ecs.get(1);
-        }
         tick() {
           this.destroyEntity(1);
         }
@@ -225,8 +221,6 @@ test('schedules entities to be deleted when ticking systems', () => {
   ecs.system('Despawn').active = true;
   ecs.create();
   ecs.tick(1);
-  expect(entity)
-    .to.not.be.undefined;
   expect(ecs.get(1))
     .to.be.undefined;
 });
diff --git a/app/ecs/system.js b/app/ecs/system.js
index 3f9454f..86895a4 100644
--- a/app/ecs/system.js
+++ b/app/ecs/system.js
@@ -10,6 +10,10 @@ export default class System {
 
   ecs;
 
+  elapsed = 0;
+
+  frequency;
+
   queries = {};
 
   constructor(ecs) {
@@ -45,8 +49,6 @@ export default class System {
     }
   }
 
-  finalize() {}
-
   async insertComponents(entityId, components) {
     return this.ecs.insert(entityId, components);
   }