Everyone needs a text, a trinket and a randomisation tool. The GM needs a book from a different roleplaying game. Dim the lights, sit in a circle (on the floor if you can). Put your text, trinkets and tools in the middle. GM, turn to a random page in your book and read it in its entirety. Take it seriously. The world ended a thousand years ago. You are knowledge keepers, collecting divine fragments from the past. Whenever you attempt an action, you must perform all your rituals correctly or the action will fail. At the end of every half-hour, time passes. Get up and explore your environment. Find a new text or trinket. Return to the circle and describe how the thing you've found combines with the objects in the centre to form a new ritual. GM, read the entirety of a different page. Read extracts from texts, perform motions with your trinkets, make dice rolls or coin flips and explain how the result is a sign from your gods. Do not make your rituals easy. When your accumulated rituals become too hard for you to perform every time, describe how your rituals caused the world to end again.
Thank you to the LoadingReadyRun discord and in particular Cherubim, Paranundrox and Nate for helping me workshop this idea