Unity particle thrower.

ParticleThrower.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class ParticleThrower : MonoBehaviour {
	public class ParticleData {
		public Rigidbody2D body;
		public Vector2 force;
		public float torque;

		public ParticleData (Rigidbody2D body, Vector2 minForce, Vector2 maxForce, float torqueMin, float torqueMax) {
			this.body = body;

			float forceX = Random.Range(minForce.x, maxForce.x);
			float forceY = Random.Range(minForce.y, maxForce.y);
			force = new Vector2(forceX, forceY);

			torque = Random.Range(torqueMin, torqueMax);
		}
	}

	// Storage of pre-calculate particle throwing
	List<ParticleData> particles = new List<ParticleData>();

	[Tooltip("Immediately throw when enabled")]
	[SerializeField] bool throwOnEnable;

	[Tooltip("Use this heading if throwOnEnabled is checked")]
	[SerializeField] float headingX = 1f;

	[Tooltip("How long to wait before removing items from the scene. Leave at 0 to never cleanup")]
	[SerializeField] float cleanupDealy = 20f;

	[Tooltip("Over how long a period of time will items fade out")]
	[SerializeField] float fadeTime = 3f;

	[Tooltip("Random throw ranges")]
	[SerializeField] Vector2 minForce = new Vector2(200f, 0f);
	[SerializeField] Vector2 maxForce = new Vector2(350f, 100f);

	[SerializeField] float minTorque = 50f;
	[SerializeField] float maxTorque = 90f;

	void Awake () {
		// Pre generate throw data to prevent fps hiccups
		foreach (Transform child in transform) {
			particles.Add(
				new ParticleData(child.GetComponent<Rigidbody2D>(), 
			                     minForce, maxForce, 
			                     minTorque, maxTorque)
			);
		}
	}

	void Start () {
		if (throwOnEnable) Throw(headingX);
	}

	public void Throw () {
		Throw(headingX);
	}

	public void Throw (float headingX) {
		headingX = Mathf.Clamp(headingX, -1f, 1f);

		// Force detach particles from object since it will be destroyed
		transform.parent = transform.parent.parent;

		foreach (ParticleData part in particles) {
			part.force.x *= headingX;
			part.torque *= headingX;

			part.body.AddForce(part.force);
			part.body.AddTorque(part.torque);
		}

		particles = null;

		if (cleanupDealy != 0f) {
			StartCoroutine(Cleanup(cleanupDealy, fadeTime));
		}
	}

	IEnumerator Cleanup (float delay, float fadeTime) {
		yield return new WaitForSeconds(delay);
		SpriteRenderer[] sprites = GetComponentsInChildren<SpriteRenderer>();

		float timer = 0.0f;
		
		while (timer <= 1.0f) {
			foreach (SpriteRenderer s in sprites) {
				Color c = s.color;
				c.a = 1f - timer;
				s.color = c;
			}
			
			timer += Time.deltaTime / fadeTime;
			yield return null;
		}

		// Clear self
		Destroy(gameObject);
	}
}