This update is kind of a strange one: it's sort of a major update, because it adds a whole new scenario that's unlocked right from the start. But it's sort of a minor update, because that scenario is a free-form Sandbox mode where it's impossible to win (or lose!), but you can build freely and explore.
I'm not a big "sandbox" kind of player myself, but even I lost a few more hours than I'd care to admit just chilling out and building a giant island without having to worry about mana. If that's your thing – if you just want to plop tiles for a bit and relax – this update is for you!