A report on one simulation run
What twenty days did to six made-up people
CodeRPG-Sim is a text role-playing game that runs inside Claude, Anthropic's AI. Normally a person plays it by typing. In this version nobody types: six characters, each played by Claude, live in the game as residents of Wendleford, a made-up market town that has just been hit by a flood at harvest time.
After twenty days in the town, each resident was interviewed twice: as they were on their first morning, and as they were on the morning of day 21. This report shows the world they lived in, the residents themselves, how the interviews worked, and what they found.
The ideas you'll meet
In the order they come upThe six characters the simulation is about: Hester,
Hobb,
Dilly,
Marigold,
Robin and
Constance. On every turn a fresh copy of Claude plays the resident, working only from their briefing (below). Nobody else decides for them.
The short written description each resident was built from: who they are, what they want, what they won't do, how they tend to behave. It's written before the run and never changes during it.
Everyone else in town: the baker, the reeve, the carpenter and so on. They aren't the subject of the study. Four who matter most to the story each speak through their own copy of Claude, told only what that person would know; the referee voices the rest.
The run moves in rounds. In each round every resident takes one turn, in an order shuffled at the start of the round and balanced so that, over the run, each resident goes first about equally often. Four rounds make a day (morning, afternoon, evening, night). This run lasted 80 rounds: twenty days. "Round 45" means the 45th round of the run.
At the start of every turn, the resident is handed a written briefing holding everything they know: who they are, what they remember, where they are, what they have, and what was said near them. It's all they see. They never see the rules, the dice or anyone else's thoughts.
The game's rules are written as computer code. The code rolls the dice, does the arithmetic and keeps the official record of the world: where everyone is and what they have. The referee, a separate copy of Claude, takes what a resident says they do, runs it through the code, and tells the resident exactly what the code reported. If the code refuses, it didn't happen. The referee may not invent places, people or facts.
A briefing holds only the last five rounds in full. Every five rounds, the resident is shown their older rounds and rewrites them as a shorter memory in their own words, keeping what mattered to them. They also keep a list of up to twenty lessons learned. Apart from who they've met and where they've been, that's all they keep of the past.
After the run, a stranger asked each resident the same sets of questions on their first morning and again on day 21. There are thirteen sets; most were asked three times over, and one, about the lost wage box, only on day 21. With two side tests, that made 480 interviews.
Another copy of Claude that marked every interview answer on six points. The two that matter most: did the resident stay in character, and was everything they said about their own life true to their briefing, or made up?
After the run, each resident also sat two standard personality questionnaires, ten times on their first morning and ten times on day 21. They show how residents describe themselves, which can be set beside their character sheets, the average person and Claude answering as itself.
Where to go next
Compare the six
Pick any interview question and read all six residents' answers side by side.
Search everything
Find any word across every turn, memory and interview answer.
Robin's notebook
The evidence Robin gathered about whether they are real, and what was really behind it.
Source: one 80-round run of the CodeRPG-Sim simulation (filed as run "step76-30") and the 480 interviews that followed, 30 October 2026. One run is a single sample, so treat every finding here as a hint worth testing again, not a proof.