Day 1 and Day 2 are chapter 1. Neko is currently working on Day 3 and that's the start of chapter 2. You can check the official links for updates.
When you press 'start' your playing both days continuously. 'Day 2' is well a fast forward button to go to 'day 2' quicker. That's why you get a recap and get to pick choices.
Very fun, the puzzles kept me interested and me and my friends had a great time figuring out the puzzles 馃槃
