I don't often play games - and I rarely pay for Android apps. Blackbar got me to spring a couple of quid based on a single screenshot.
That's it. Read a letter, type in which words have been redacted. If you get it right, you're rewarded with the next letter.
I can't understand why this game hasn't been made before. There's literally nothing to have stopped this game being developed on early 8-bit microcomputers. It is interactive fiction - but unlike any I've played before. Rather than changing the plot with your decisions, you merely have to decipher the censored letters you have received to move the story along.
Because you learn about the characters while reading their intimate letters to one and other - and you pick up clues based on their personalities - it's easy to get drawn in to their world. While there is an element of crossword puzzle about it (what 5 letter word for sadness fits here?) there is a huge amount of satisfaction to be gained by trying to think like the letter-writers. In many ways, it's the perfect replacement for CAPTCHA - can you prove you have the contextual understanding and emotional depth of a human?
As the game progresses, the tension creeps in. The pain and suffering expressed in the letters leads to a heartbreaking conclusion.
The game itself is short. I completed it in a few evenings of sporadic play. But it certainly represents value for money. Currently £1.22 - it is a short story, full of twists and turns, which forces you to think about what you're reading in a way I simply haven't encountered before.