Curses

I'm of an age so I remember playing adventure games on 8 bit computers... I was bored and discovered google's "Twisty" app for android and thought I'd give it a go. It comes with Curses pre-loaded. Without a walkthrough and lashings of hints I'd have got nowhere. But even with a heavy dose of cheating and a poor input device the game is still totally absorbing.
I would have given it five if I thought for a minute that anyone had actually completed this game without external help.
Still I suppose it's a little like cryptic crossword clues.. the more you do it, the better you get.