The way I made those was having a subdivided plane with a bunch of holes in it rotate in front of a halo spotlight.
Unfortunately, you cannot use halos in the game engine.
You’ll have to make several prisms set to shadeless and with a material that is semi-transparent.
Then you can add an always sensor that plays the IPO.
Then you’ll have to add some rotation and scale to them. Take a look at this script. It creates random movement and you can specify details.
In the scripts window, under animation, there’s a bake constraints to IPO. After you do that, select each one and move it’s IPO just a little bit so they aren’t all the same.
I made a quick example. It’s not the best, so you might want to remake one yourself. Hope it’s helpful.
I haven’t found a good upload place yet for files that are bigger than 1MB. This one’s on megaupload. Do you know the best site to upload files?