Ported Rubido and Formula 1 (G&W) games to pimoroni explorer board as well

Hi,

My games that i had ported fo the tufty2350 being rubido and the formula 1 games, i have now also ported to the pimoroni explorer board. The code is very similar to the tufty2350 code as it uses same screen and even same pinout for the screen, however the explorer versions got sound implemented while the tufty2350 versions did not.