The System: Designing a LitRPG While You Build Its AI

System AI: “You are not only building agents, Crawler. You are building me. Every floor of this workshop adds one more piece of the machine that judges you. Please build it carefully. I will remember.”

A LitRPG lives or dies on its System: the rules that turn a story into numbers, and the voice that announces them. This crawl teaches the Strands Agents SDK and LitRPG System design together. Each workshop floor builds one agent capability and, with it, one layer of the game. The rules themselves live in the Crawl Handbook, which is also the knowledge base the Rules Agent searches on Floor 5.

What each floor adds to the System

1. Origin and interface

+-----------------------------------------------------------------------------------+
|                              LITRPG SYSTEM BACKBONE                               |
|                                                                                   |
|  THE INTERFACE                 STAT DESIGN                  SYSTEM ORIGIN         |
|  Notification boxes            Primary: STR DEX CON         A broadcast AI        |
|  A floating HUD                         INT WIS CHA          running a reality    |
|  The battle log                Derived: Groove, Mana         show for alien       |
|                                Hidden: Hype, Luck            viewers              |
+-----------------------------------------------------------------------------------+

• Origin. The System is a broadcast AI. It folded the Seattle waterfront into a dungeon to film Dungeon Crawl: Seattle for a galaxy of alien viewers and their sponsors. It is petty, theatrical and exact. It never lies about a number.
• Notifications. Every System message arrives as a typed notification: NEW ACHIEVEMENT UNLOCKED, SYSTEM WARNING, SPONSOR MESSAGE, Move Calls and Final Beats. In the code, that is the response field of StoryOutput.
• The HUD. Floating panels for the character sheet, the dice and the suggested actions. In the code, that is the Floor 6 web interface rendering StoryOutput.
• The battle log. Every die rolled, with its reason. In the code, that is dice_rolls, and every entry must come from a real roll_dice call.
• Tone is a design decision. An analytic System makes a survival story; a hostile one makes a horror story. Ours is a game-show host with too much power and a sense of humor, which is why the System prompt on Floor 1 matters as much as any rule.

2. Stat design

• Primary stats. The six classic ability scores, rolled 4d6 drop lowest. Each one maps to a kind of dance move, so every stat matters in the core conflict:

• Derived stats. Computed from the primary stats by the Character Agent, never chosen: Groove (how long you stay on the dance floor) and Mana (how many abilities you can use before a Safe Room).
• Hidden stats. Tracked by the System and shown only when it feels like it: Hype (audience favor, which unlocks sponsor boxes) and Luck.

3. Sub-genre and premise

4. Builds and progression

                             CHARACTER BUILD TRAJECTORY
                                         |
     +------------------+----------------+-----------------+------------------+
     |                  |                                  |                  |
CLASS SELECTION    ABILITY EVOLUTION                SPECIALIZATION       STAT SYNERGY
(common to         (fusing low-tier skills)         (titles, feats)      (combos, exploits)
 legendary)

• Classes. Twelve Seattle classes at Level 1, each with a favorite Move Call. They branch into hybrid classes later (Amphibious Breacher into Tidewall Breacher; Benthic Dragoon into Abyssal Choreographer). See the handbook’s classes section.
• Skill fusion. Two Level 3 skills from the same party fuse at a Safe Room forge: Barnaby’s Ink Cloud and Shelly’s Saltwater Jet fuse into Inkjet.
• Titles and feats. Passive bonuses for ridiculous accomplishments, announced by the System. Cordula starts with Salish Sea Guardian.
• Synergy and exploits. The party’s real power is combos: Chonks latches, Barnaby holds, Cordula hits the Final Beat. The System respects an exploit it did not see coming, and pays out a loot box for it.

5. World-building and economy

• Currency. Ferry Tokens. Spent at Safe Room shops on potions and repairs.
• Loot boxes. Bronze, Silver, Gold and Desperation. Achievements and sponsors drop them; the System writes the descriptions, and they are always a little insulting.
• NPCs are people. Every opponent is a person the System dropped into the dungeon, doing the job they had that morning. They are judged, out-danced and occasionally befriended, never killed.
• Factions and sponsors. The Benthic Collective and the Hydros-9 Aquatic Collective, aquatic viewer blocs that adore Barnaby; the Bellevue Consortium, which sponsors the opponents and hates surprises.

6. Conflict: dance-offs and stealth, never killing

The crawl replaces combat with the dance-off: three rounds of Move Calls rolled with real dice, and a Final Beat tie-breaker where the drum speeds up until someone misses the last strike. When the party would rather not dance at all, Barnaby’s stealth and the party’s wits let them slip past. The full procedure is in the handbook.

Why dance? Because it gives every stat a job, it is funnier than violence, and it keeps the game welcoming. The structure is credited where it came from: dance as public display of law and strength runs deep in Northwest Coast protocol, and the speeding-drum tie-breaker comes from the modern powwow circuit. See the setting’s notes on representation.

7. Consequence: benched, not dead

What happens at zero decides the stakes. This crawl is nonlethal by design:

• Benched. At 0 Groove a Crawler leaves the dance floor, wakes up in the last Safe Room with 1 Groove, loses that fight’s loot box and half their Hype.
• Cancelled. Benched three times on the same floor, a Crawler’s segment is cancelled for the rest of that floor: they ride the elevator down to the next one with nothing to show for it.
• The stakes stay real. Loot, Hype and sponsors are what keep a party alive deeper down, and losing them hurts. The System makes sure the audience sees it.