diff --git a/backend/package.json b/backend/package.json
index b951a29..1149e30 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -1,6 +1,6 @@
 {
   "name": "declared-server",
-  "version": "0.0.13",
+  "version": "0.0.15",
   "description": "Game server for decla.red",
   "keywords": [],
   "author": "András Schmelczer <andras@schmelczer.dev> (https://schmelczer.dev/)",
diff --git a/backend/src/default-options.ts b/backend/src/default-options.ts
index a43f5f0..5a1c729 100644
--- a/backend/src/default-options.ts
+++ b/backend/src/default-options.ts
@@ -4,7 +4,7 @@ export const defaultOptions: Options = {
   port: 3000,
   name: 'Test server',
   playerLimit: 16,
-  npcCount: 12,
+  npcCount: 16,
   seed: Math.random(),
   scoreLimit: 1000,
   worldSize: 8000,
diff --git a/backend/src/objects/circle-physical.ts b/backend/src/objects/circle-physical.ts
index 9601012..d6b29e8 100644
--- a/backend/src/objects/circle-physical.ts
+++ b/backend/src/objects/circle-physical.ts
@@ -1,5 +1,11 @@
 import { vec2 } from 'gl-matrix';
-import { Circle, CommandReceiver, GameObject, serializesTo } from 'shared';
+import {
+  Circle,
+  CommandExecutors,
+  CommandReceiver,
+  GameObject,
+  serializesTo,
+} from 'shared';
 import { BoundingBox } from '../physics/bounding-boxes/bounding-box';
 import { BoundingBoxBase } from '../physics/bounding-boxes/bounding-box-base';
 import { moveCircle } from '../physics/functions/move-circle';
@@ -17,6 +23,10 @@ export class CirclePhysical extends CommandReceiver implements Circle, DynamicPh
 
   private _boundingBox: BoundingBox;
 
+  protected commandExecutors: CommandExecutors = {
+    [ReactToCollisionCommand.type]: this.onCollision.bind(this),
+  };
+
   constructor(
     private _center: vec2,
     private _radius: number,
diff --git a/backend/src/objects/planet-physical.ts b/backend/src/objects/planet-physical.ts
index 094b48d..73ba674 100644
--- a/backend/src/objects/planet-physical.ts
+++ b/backend/src/objects/planet-physical.ts
@@ -153,7 +153,7 @@ export class PlanetPhysical extends PlanetBase implements StaticPhysical {
 
   public getForce(position: vec2): vec2 {
     const diff = vec2.subtract(vec2.create(), this.center, position);
-    const dist = Math.max(0, vec2.length(diff) - 600);
+    const dist = Math.max(0, vec2.length(diff) - this.radius);
     vec2.normalize(diff, diff);
     const scale = clamp(
       settings.maxGravityQ * ((settings.maxGravityDistance / dist) ** 1.5 - 1),
diff --git a/frontend/src/scripts/join-form-handler.ts b/frontend/src/scripts/join-form-handler.ts
index 93a34a0..e9c597c 100644
--- a/frontend/src/scripts/join-form-handler.ts
+++ b/frontend/src/scripts/join-form-handler.ts
@@ -82,15 +82,17 @@ export class JoinFormHandler {
 
       if (response?.ok) {
         const content: ServerInformation = await response.json();
-        const server = new ServerChooserOption(
-          content,
-          url,
-          this.removeServer.bind(this),
-          this.servers.length === 0,
-        );
-        this.servers.push(server);
-        this.joinButton.disabled = false;
-        this.container.appendChild(server.element);
+        if (!this.servers.find((s) => s.url === url)) {
+          const server = new ServerChooserOption(
+            content,
+            url,
+            this.removeServer.bind(this),
+            this.servers.length === 0,
+          );
+          this.servers.push(server);
+          this.joinButton.disabled = false;
+          this.container.appendChild(server.element);
+        }
       }
     });
   }
diff --git a/shared/src/objects/types/planet-base.ts b/shared/src/objects/types/planet-base.ts
index 9d1d526..9adb944 100644
--- a/shared/src/objects/types/planet-base.ts
+++ b/shared/src/objects/types/planet-base.ts
@@ -8,6 +8,7 @@ import { Id } from '../../communication/id';
 @serializable
 export class PlanetBase extends GameObject {
   public readonly center: vec2;
+  public readonly radius: number;
 
   constructor(
     id: Id,
@@ -17,6 +18,9 @@ export class PlanetBase extends GameObject {
     super(id);
     this.center = vertices.reduce((sum, v) => vec2.add(sum, sum, v), vec2.create());
     vec2.scale(this.center, this.center, 1 / vertices.length);
+    this.radius =
+      vertices.reduce((sum, v) => sum + vec2.distance(this.center, v), 0) /
+      this.vertices.length;
   }
 
   public generatedPoints(value: number) {}
diff --git a/shared/src/settings.ts b/shared/src/settings.ts
index 75c08a6..96a6275 100644
--- a/shared/src/settings.ts
+++ b/shared/src/settings.ts
@@ -27,7 +27,7 @@ export const settings = {
   maxGravityQ: 5000,
   planetControlThreshold: 0.2,
   playerMaxHealth: 100,
-  maxGravityStrength: 10000,
+  maxGravityStrength: 50000,
   maxAcceleration: 120000,
   playerMaxStrength: 80,
   endGameDeltaScaling: 2,