light gradient images

Image assets for a game in which the player's view is constricted to a small ring of light.

In Pygame the assets are used as follows:

• gradient image is loaded
• all black, stage-sized drawing surface is created (darkness overlay)
• the gradient image is blited (copied) on to the darkness overlay using Additive blending (white lighten)
• the darkness overlay is blited on to the screen using Multiplicative blending (black darkens)