Similar to what other folks are saying. I get the ROT13 piece, but still - the program on the right I do not understand what does FLAG mean, what does GOTO mean - what's with the numbers with $ v. the numbers without? The tutorial gives a program on the right that's simply unlock, so it doesn't really help me understand what I'm doing with these cards.
Full points on the secrets theme. Like the idea of a Captcha for humans