Rolling demo showing scrolling multicolour graphics on a ZX Spectrum in an imitation of Activision's classic 'River Raid'.

'Multicolour' is a software timing technique that increases the colour resolution of the ZX Spectrum screen, here giving separate colours to every 8x1 pixels of the screen instead of every 8x8 character cell, allowing for vertical pixel-precise colours and scrolling. Though only in the middle 50% of the screen.

With some synchronised trickery, the horizontal roads appear not just across the full screen width, but into the border area too.