To celebrate 20 years of PlayStation, Sony unveiled a new retro-styled PS4 that just oozes nineties nostalgia. But what about the millions of us who already own a PlayStation 4? Don't worry, Sony has you covered too. If you head on over to the PlayStation Store, there's a new Anniversary theme that mimics the look and the startup sound of the PSone. The free pack is actually available for PlayStation 4, PlayStation 3 and PS Vita and has just begun rolling out in Europe. Download, listen (there are a couple of other easter eggs) and enjoy.