The most efficient method would be with a custom shader. The second most efficient method is likely to be a set of images animated on plane or a GUITexture in front of the camera. You will find code here to animate a set of images.

http://wiki.unity3d.com/index.php?title=Texture_swap_animator

A less efficient method is to dynamically calculate changes in a texture:

• Create a Quad (Game Object > Create Other > Quad).

• Move the Quad directly in front of the camera just in front of the camera and just in front of the near clip plane of the camera

• Make the Quad a child of the camera

• Create a material using the Unlit/Transparent shader and apply it to the Quad (no need for a texture)

• Add the script below to the Quad.

  ---

  pragma strict

  var lineFrequency = 5; var updateFrequency = 5.0;

  private var tex : Texture2D; private var pixels : Color32[]; private var mat : Material;

  function Start () { mat = renderer.material; tex = new Texture2D(255, 255); var c32 = Color32(0, 0, 0, 0); pixels = tex.GetPixels32(); for (var i = 0; i < pixels.Length; i++) { pixels[i] = c32; } tex.SetPixels32(pixels); tex.Apply(); mat.mainTexture = tex;

     InvokeRepeating("UpdateStatic", 0.0, 1.0/updateFrequency);
   }
   
   function UpdateStatic() {
       for (var i = 0; i < pixels.Length; i++) {
           if ((((i / tex.width ) % lineFrequency) == 0 ))
               pixels[i].a = Random.Range(85, 101.0);
           else
               pixels[i].a = Random.Range(0, 25);
       }
       
       tex.SetPixels32(pixels);
       tex.Apply();
       mat.mainTexture = tex;
   }
  
  

There are a number of things here to play with to get the effect the way you want:

• The size of the texture and the line frequency will effect the softness/hardness of the lines...and will also have an impact on efficiency.

• The Random.Range() calls determines the look of the static for both lines and non-line areas.

• 'updateFrequency determines the rate at which the static refreshes.

In here, this person explains how to create a Slender game in detail using Unity Free version. http://www.youtube.com/watch?v=JXDBNNE4aFY

He speaks in Portuguese but it's pretty much clear how he does that, so here you go.