This is really a really fun match-2 game: there are 12 book covers which consist of 2 editions of 6 different books. No titles or author names. The game is to match the books by the covers alone.
Some are a little more obvious than others. Some are guessable and some are like “what!?” They reveal the answer after clicking one book, so it’s possible to examine the rest to figure out the best match. A more challenging game will be titles are revealed after 2 covers are clicked.