I was able to hang at around 0.5 by remembering something I'd read on HN about identifying non-random strings because they did too much alternating and not enough repeating.<p>Instead of trying to pick randomly between f and d, I picked numbers between 0 and 9, with an intentional bias toward lower numbers, and those would determine the length of the next sequence. So if I picked 4, 3, 7, 1, 3, 2, 2, 5, 0, 4 as my numbers, that would translate to<p>ddddfffdddddddfdddffddfffff[0=don't change]ffff.<p>I suspect a more sophisticated program would be able to pick apart my strategy, but it worked really well against this particular algorithm.