diff --git a/engine/system/physics.ts b/engine/system/physics.ts
index f65108e..3bde81f 100644
--- a/engine/system/physics.ts
+++ b/engine/system/physics.ts
@@ -43,27 +43,10 @@ function createCollisionBuffer(size: number): CollisionBuffer {
 	};
 }
 
-function bufferNext(buffer: CollisionBuffer): Collision {
+function next(buffer: CollisionBuffer): Collision {
 	return buffer.pool[buffer.cursor++ & buffer.mask];
 }
 
-function bufferSliceReset(buffer: CollisionBuffer): void {
-	buffer.slice.length = 0;
-}
-
-function bufferSliceAdd(buffer: CollisionBuffer): Collision {
-	const next = bufferNext(buffer);
-	buffer.slice.push(next);
-
-	return next;
-}
-
-export type Collider = {
-	shape: ShapeType;
-	body: Circle | Rect | Polygon;
-	buffer: CollisionBuffer;
-};
-
 export type Collision = {
 	cid: string;
 	normal: Vector;
@@ -82,16 +65,25 @@ function createCollision(): Collision {
 	};
 }
 
-export function createCollider(
-	shape: ShapeType,
-	body: Circle | Rect | Polygon,
-	bufferSize: number = 8,
-): Collider {
-	return {
-		shape,
-		body,
-		buffer: createCollisionBuffer(bufferSize),
-	};
+export class Collider {
+	shapeType: ShapeType;
+	body: Circle | Rect | Polygon;
+	buffer: CollisionBuffer;
+
+	constructor(
+		shape: ShapeType,
+		body: Circle | Rect | Polygon,
+		bufferSize: number = 8,
+	) {
+		this.shapeType = shape;
+		this.body = body;
+		this.buffer = createCollisionBuffer(bufferSize);
+	}
+
+	// FIXME: sTruCtUrEd ClOnE >.<
+	collideWithCircle(collision: Collision, cid: string): void {
+		collision.cid = cid;
+	}
 }
 
 export function moveAndCollide(
@@ -100,16 +92,34 @@ export function moveAndCollide(
 	delta: number,
 ): Array<Collision> {
 	const colliders = $<Collider>("collider")!;
-	const self = colliders.get(id)!.value;
-	bufferSliceReset(self.buffer);
+	const self = colliders.get(id)!;
+	console.log(id, self);
+	const slice = self.value.buffer.slice;
+	slice.length = 0;
 
-	for (const [cid, _] of colliders.entries()) {
+	for (const [cid, collider] of colliders.entries()) {
 		if (cid === id) {
 			continue;
 		}
-		const collisoin = bufferSliceAdd(self.buffer);
-		collisoin.cid = cid;
+
+		const collision = next(self.value.buffer);
+		switch (collider.value.shapeType) {
+			case CIRCLE: {
+				// FIXME: sTruCtUrEd ClOnE >.<
+				self.value.collideWithCircle(collision, cid);
+				break;
+			}
+			case RECT: {
+				break;
+			}
+			case POLYGON: {
+				break;
+			}
+		}
+		if (collision.cid.length > 0) {
+			slice.push(collision);
+		}
 	}
 
-	return self.buffer.slice;
+	return slice;
 }
diff --git a/game/entities/hero/entity.ts b/game/entities/hero/entity.ts
index 78a8e4f..905bba4 100644
--- a/game/entities/hero/entity.ts
+++ b/game/entities/hero/entity.ts
@@ -9,7 +9,7 @@ import {
 	defineSpriteSheet,
 } from "#/engine/Sprite.ts";
 import {
-	createCollider,
+	Collider,
 	moveAndCollide,
 	Shape,
 } from "#/engine/system/physics.ts";
@@ -24,7 +24,7 @@ const process = defineEntity("hero", {
 	sprite: createSprite(idleSrc),
 	animation: createSpriteAnimation(500, 2),
 	velocity: createVector(),
-	collider: createCollider(Shape.Cirle, createCircle(createVector(), 8)),
+	collider: new Collider(Shape.Cirle, createCircle(createVector(), 8)),
 });
 
 process((id, delta) => {
diff --git a/game/entities/portal/entity.ts b/game/entities/portal/entity.ts
index 2c7b0f0..d2b0bb8 100644
--- a/game/entities/portal/entity.ts
+++ b/game/entities/portal/entity.ts
@@ -5,7 +5,7 @@ import {
 	createSpriteAnimation,
 	defineSpriteSheet,
 } from "#/engine/Sprite.ts";
-import { createCollider, Shape } from "#/engine/system/physics.ts";
+import { Collider, Shape } from "#/engine/system/physics.ts";
 import { createVector } from "#/engine/Vector.ts";
 import portal from "#/game/assets/portal.png";
 
@@ -15,5 +15,5 @@ defineEntity("portal", {
 	position: createVector(),
 	sprite: createSprite(portalSrc),
 	animation: createSpriteAnimation(400, 0),
-	collider: createCollider(Shape.Cirle, createCircle(createVector(), 8)),
+	collider: new Collider(Shape.Cirle, createCircle(createVector(), 8)),
 });