What is the secret achievement in the game? I've got all but that & Jennifer. I'm fairly certain that it can't be getting a score that ends with 42, so unless it's a "get everything" achievement, I'm out of ideas.
Playing on my android device, the secret achievement is titled:
"How Very Social of You." You can find the name of the achievements on Github looking through the code.
It's unlocked by:
Pressing one of the social media buttons at the bottom of the screen when you are choosing what board to play. I pressed the Twitter button and the achievement unlocked. However, the game did nothing. This could be because I don't have twitter installed on my device. Pressing the Facebook button prompted me to share the game to Facebook.