You can choose if you want to play every route in the game (specially now that we're on a public build hiatus lol) but what I meant is that the developers are updating the story of the game giving a single route a specific day, per update.
For example: Imagine they just added Lars day 7 but the rest of the routes stop at day 6, now for the next months they'll update the 7th day to all of the possible routes separately (Beginning month: Lars day 7, one month later: Gil day 7, two months later: Parker day 7, three months later: Mark day 7, etc.) and once every route has their own 7th day, just then we'll move on to day 8 and continue this cycle until the story ends at day 14.
About the heads at the bottom... those are special episodes (not tied to main story) waiting to be added to the public version!