My First Raspberry Pi Game -- Part 10 -- Red square

Andy Balaam shows you how to write your first ever computer program on the Raspberry Pi ultra-cheap computer. This episode: finally the much-promised red square will appear on the screen; the player has to avoid pressing a key when they see it. There are detailed notes at: http://www.artificialworlds.net/blog/2012/12/14/my-first-raspberry-pi-game-part-10-red-square/