I was recently working on a remaster of Flash Gordon for digital pinball enthusiasts. I created a new apron design which is kind of funky. In the 'Modern Retro' version of Flash Gordon, I added a feature where you can switch between the original game and rules to the remastered version in an instant by holding up both flippers for 2.5 seconds. A pretty cool feature, which is why it says 'retro switch' on the apron art.