Also, I've played a bit now and I've successfully gotten the word twice. In reality I think the difficulty is too high for it to have enough of a retention sort of hook.
I think you might be right that it's a matter of practice, but retention is an issue. Flappy Bird already has an inherent difficulty increase (speed increase), so you could keep the words coming in infinitely with the speed increasing as you get each word correct.
True. I think it'd be better to make the solution accessible earlier rather than later. Past that point, I can increase the difficulty.