ParticleSystem.MainModule.startRotationXMultiplier

Description

The initial rotation multiplier of particles around the x-axis when the Particle System first spawns them.

Changing this property is more efficient than accessing the entire curve, if you only want to change the overall rotation multiplier.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    private ParticleSystem ps;
    public float hSliderValue = 1.0F;

    void Start()
    {
        ps = GetComponent<ParticleSystem>();

        var main = ps.main;
        main.startRotation3D = true;

        var psr = GetComponent<ParticleSystemRenderer>();
        psr.material = new Material(Shader.Find("Sprites/Default"));    // this material renders a square billboard, so we can see the rotation
    }

    void Update()
    {
        var main = ps.main;
        main.startRotationXMultiplier = hSliderValue;
    }

    void OnGUI()
    {
        hSliderValue = GUI.HorizontalSlider(new Rect(25, 45, 100, 30), hSliderValue, 0.0F, 360.0F * Mathf.Deg2Rad);
    }
}