This jam is now over. It ran from 2023-06-21 05:00:00 to 2023-09-21 05:00:00. View 15 entries

What is MOSAIC Strict?

For a full primer on the MOSAIC Strict design philosophy, make sure to read the blog article Nothing at the Bottom: MOSAIC Strict RPG Design by Michael Prescott. It's an approach to creating modular rules text that can be slotted into most rules-lite systems or combined to create a uniquely custom experience. To briefly summarize, the acronym MOSAIC stands for: 

  • Modular: Any game text that explicitly claims to bean entire, complete RPG is not Mosaic Strict.
  • Optional: Any game text that describes itself as necessary for play is not Mosaic Strict.
  • Short: Mosaic Strict game texts are no more than 1500 words.
  • Attested: Mosaic Strict texts say they are Mosaic Strict.
  • Independent: Mosaic Strict texts do not refer to the mechanics or quantified state in any other game text.
  • Coreless: assume nothing else is in use beyond free-form play

What are the Rules for this Jam?

There are very few rules for the jam, as its primary purpose is a casual creative exercise in working within constraints, establishing a daily creative habit for designers, and increasing the overall available of novel & interesting MOSAIC Strict modules out in the wild.

At the end of this page are 30 short design prompts -  create a short TTRPG supplement following the MOSAIC framework described above. It can be anything - an adventure, character creation system, combat rules, classes. The intention is to create one a day, going down the list of prompts in order.  You are welcome to interpret the prompts in any way you wish, so long as it adheres to the MOSAIC Strict design philosophy.

What if I start late / fall behind?

While the intention is one prompt a day for 30 days, the jam itself will take submissions for a bit longer than a month. You're also perfectly welcome to skip days, do prompts out of order, or do multiple prompts a day if the spirit moves you. The goal is to have fun & explore new creative spaces.

The Prompts:

  1. Unconventional Magic
  2. Cursed Artifacts
  3. Cooperative Worldbuilding
  4. Dynamic Environments
  5. Building Character
  6. Transformative Items
  7. Player-Driven Narrative
  8. Parallel Realities
  9. Moral Dilemmas
  10. Mythical Beasts
  11. Subterfuge and Intrigue
  12. Living Ecosystem
  13. Experimental Technology
  14. Dreams and Nightmares
  15. Ethereal Entities
  16. Cultural Clashes
  17. Time Travel Shenanigans
  18. Intricate Puzzles
  19. Natural Disasters
  20. Living Legends
  21. Unreliable Narrators
  22. Cosmic Scale
  23. Magical Artistry
  24. Supernatural Ailments
  25. Technomancy
  26. Lost Civilizations
  27. Shapeshifting
  28. Non-Combat Resolution
  29. Haunted Places
  30. Epic Journeys


Credit for the Bookmarklet Icon used in the banner to Lorc via


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A MOSAIC Strict phenomenon to include in your horror games
A MOSAIC Strict table of magical items with a modern twist!
A MOSAIC Strict System for handling overpowered abilities and tech.
MOSAIC Strict rules for creating player-driven narratives
A MOSAIC Strict module for running a city on the back of a flying leviathan
A MOSAIC Strict Setting and Table for Enchanted Drinks
A MOSAIC Strict ruleset for building maps and establishing setting details as a group for any TTRPG system
Easily extendable MOSAIC Strict rules for creating, progressing, and playing characters
A high risk, high reward MOSAIC Strict magic system
MOSAIC Strict FRESCO Friendly Cube of MagiTech
MOSAIC Strict FRESCO Friendly Way of Travel
MOSAIC Strict FRESCO Friendly Random Place
The severed head of a Lich trapped in a jar, can it be trusted? A MOSAIC Strict cursed artifact
A MOSAIC Strict module for an unreliable utility item
MOSAIC-strict module for enhancing concoctions