"The plot centers around "rarities," specific characters with special upgradeable superpowers we can use while possessing them and whom we bring along on all our missions. And there are several side ones we can unlock from doing optional objectives. Except every now and again the plot stops dead, sits down, sticks out its lower lip like a little toddler, and goes, "I'm not continuing until you find all the optional characters." Well they're not fucking optional, then, are they! And I wouldn't mind, but most of these characters proceed to have bugger-all importance to the plot. It's like if the Beatles held up a song writing session to wait for Ringo to arrive."