Official UK PlayStation Magazine Vol. 16 Demo Disk Easter Egg - Star Fighters (Hidden Game)

1. Load the demo in your PlayStation.
2. Hover over the "Forsaken" demo
3. Hold and Press L1 + L2 + R1 + R2 + Up + X*

If you're successful (it can be quite tricky), a space backdrop will appear talking about "aliens" before displaying the title of "Star Fighters." You can then play a very short Gradius style game.

*L1 + R1 + Up + X also has a tendency to work.