Changes in response to second round of user testing
player one and two have seperate keys (Wasd vs udlr)
keys are shown to player as part of tutorial
players can skip some of the onscreen text (mainly tutorial)
sequence lengths get much longer to cater for players with better memorys
coloured text reflects player turn - white text reflects an instruction
the tutorial inserts are shorter and more frequent (less to read)
the text is much bigger and easier to read against the background
added minor gradient to top of play area to make it easier to read text