Twenty-four doors, one unlocked per calendar day through December, each hiding a small piece of writing or a joke specific to the Clock In Sims building. You can only open a door on its actual date — there's no skipping ahead, which is more or less the entire point of an advent calendar.
It's a small, low-stakes companion piece to the rest of the site: no scoring, no failure state, just something worth checking once a day for the run-up to Christmas. Doors you've already opened stay open if you come back to read them again.
Runs locally in your browser with nothing saved beyond your own device. Part of the Taking Time Back family of projects.