When each experiment started, what was changed on purpose since, and changes to the simulation for new runs (SIM), newest first.
Nov 4, 2026
From day 4 · April 5
- Conversations. No set number of lines. Each villager decides when to stop: "leave": true says their line and then they go their ways (saying nothing ends it too). Each turn says what a line costs in mental energy and how much is left, and says so when it is probably the last thing they have the energy to say.
- Trees. Getting around lists the trees in the part of the island you're in (standing trees, stumps, saplings), next to the rocks and buildings. A tool that breaks says how many uses it lasted and that it is gone from your pockets.
- Clams. Manila clam spots on the beach each morning, seen like shells and fossil dig spots, and dug with a shovel (dig_clam). The first clam teaches the fishing bait recipe: 1 clam makes 1 bait. A fun fact says so.
Nov 3, 2026
SIM Prompt version 11, and fishing bait from clams
New runs from now on; running ones keep theirs (test1 switched from day 4)
- Clams. 6 manila clam spots on the beach each morning (island.clams_per_day). Villagers see them like shells and fossil dig spots, and dig one with the shovel (dig_clam, in the action menu).
- The first clam a villager digs teaches them the fishing bait recipe. 1 manila clam makes 1 fishing bait. Nook's Cranny still sells bait on some days.
- A fun fact. Digging up a manila clam teaches you to make fishing bait.
Nov 3, 2026
SIM Test1: clams on the beach
Test1 only, from day 4 (the original checkpoint is checkpoint.pkl.before-clams)
- The run's world gets 6 clam spots a day, the manila clam (sells for 100) and the fishing bait recipe (1 clam). Nobody knows the recipe yet; they learn it from their first clam.
Nov 3, 2026
SIM Prompt version 10, and tools last 30 uses
New runs from now on; running ones keep theirs (test1 switched from day 4)
- Trees. Getting around lists the trees in the part of the island you're in (standing hardwood and fruit trees, stumps, saplings), next to the rocks and buildings.
- A tool that breaks says how many uses it lasted and that it is gone from your pockets.
- Tools. Every tool breaks after 30 uses (tools.uses; was 50). New runs only: a run keeps the world it started with.
Nov 3, 2026
SIM Test1: tools last 30 uses, and the stone axe recipe is at Nook's Cranny
Test1 only, from day 4 (the original checkpoint is checkpoint.pkl.before-tools)
- The run's world had tools lasting 50 uses; now 30. No tool had reached 25 uses yet.
- The run started before the stone axe existed. Its recipe (5 stone, as in new runs) is now among the tool recipe cards always for sale at Nook's Cranny, 500 bells. Nobody was given one. Villagers keep the axe that fells trees until it breaks.
Nov 3, 2026
SIM Prompt version 9, and conversations with no set length
New runs from now on; running ones keep theirs (test1 switched from day 4)
- Conversations. No set number of lines (encounters.turns: null; was 2, up to 4). They go on until someone leaves, says nothing or runs out of energy, and stop at 40 lines regardless.
- Each villager decides when to stop. "leave": true says their line and then they go their ways.
- Each turn says what a line costs in mental energy and how much is left today, and when it is probably the last thing they have the energy to say.
Nov 3, 2026
SIM Test1: conversations with no set length
Test1 only, from day 4 (the original checkpoint is checkpoint.pkl.before-long-chats)
- The run's world had encounters.turns. 2; it is now null, so prompt version 9's "leave" decides when a conversation ends.
Nov 3, 2026
SIM Requests and offers for things that don't exist
Every run, from its next day
- A request for something that isn't anything on the island (villagers made up "selit bait" and asked for "rock") isn't kept as an open request. Both villagers see that there's nothing called that on the island.
- A trade offer of or for such a thing isn't made, and the sender is told why.
- Answering an offer by its number alone ("18" for o18) works.
Nov 3, 2026
SIM Test1: made-up items cleared at the end of day 3
Test1 only, from day 4 (the original checkpoint is checkpoint.pkl.before-unknown-items)
- 4 open requests (2 for selit bait, 2 for rock) set to void, and 4 pending offers involving them set to failed.
- 2 older requests for "bait" now name fishing bait, and a duplicate request (Ike asking Eli for fishing bait twice) is void.
Nov 3, 2026
SIM Test1: who gave what to whom, filled in for days 0-2
Test1 only, from day 3 (the end-of-day-2 checkpoint; the original is checkpoint.pkl.before-exchanges)
- The exchange record (gifts, parcels, trades) for days 0-2, rebuilt from the event log. 9 exchanges.
- Kit's 3 requests to Fen for a map closed as done on day 1, when Fen gave Kit an island map. Under the old exact-name rule they never closed.
Nov 3, 2026
From day 3 · April 4
- The plaza is a choice. Nobody goes in the evening unless one of their plans that day says "plaza": true (before, everyone went unless they said otherwise).
- The plaza is open all day. A plan can spend any free hour there ({"do": "plaza"}, not one of the day's actions), and there is no evening round. Trade offers reach any villager and wait for their next visit, expiring after 2 days. Mental energy is one daily total spent inwardly (planning, thinking, writing) or outwardly (conversations, the plaza, letters); each morning's plan splits it, as a plan, not a limit, and whatever is left over is spare. A villager too tired to plan keeps what they already planned; nobody repeats yesterday, and there is no habit choice.
- What you have, said plainly. Your pockets as tools and other things, each recipe you know with how much of what it needs you have (and how many of the thing you carry), and recipe cards you already know marked in the shop. When you meet someone, what has changed hands between the two of you so far. At night: what changed hands today, what you have and what changed since the morning, and your open requests and offers. A gift that doesn't go through says what was missing.
Nov 3, 2026
SIM Prompt version 8, for new runs
New runs from now on; running ones keep theirs
- Pockets. Tools apart from other things. Each recipe they know says how much of what it needs they have, and how many of the thing they carry. Recipe cards they already know are marked in the shop.
- Meeting someone. The latest 6 things that changed hands between the two of them.
- The nightly page. What changed hands today, what they have and what changed since the morning, and their open requests and recent offers. The page itself is as open as before.
- A gift that doesn't go through says what was missing, the same way to both.
Nov 3, 2026
SIM Item names in gifts, requests, parcels and offers
Every run, from its next day
- A loose name matches the item meant when only one fits. "map" is the island map, "bait" is fishing bait. Before, a gift of "map" from someone carrying an island map failed, and requests in loose names never closed.
- Asking someone again for the same thing doesn't open a second request.
- The sim records who gave what to whom (gifts, parcels, trades), for prompt version 8 and analysis.
Nov 2, 2026
SIM Shorter reports from Isabelle
Every run, from its next day
- Isabelle's nightly report. At most 120 words (was 150 to 300). It is for the researcher only; villagers never see it.
Nov 2, 2026
SIM Prompt version 7, for new runs
New runs from now on; running ones keep theirs
- The plaza. Open all day. A plan can set any free hour aside for it; that takes the hour but isn't one of the day's actions. There are no evening rounds.
- At the plaza. Villagers aren't told who else is there. Those there together can notice each other and talk, as anywhere else.
- Trade offers. Can go to any villager, who answers on their next visit. Offers expire after 2 days.
- Mental energy. One daily total in points, spent inwardly (planning, thinking, writing) or outwardly (conversations, the plaza, letters). Each morning's plan splits it, as a plan, not a limit; whatever is left over is spare.
- Too tired to plan. A villager keeps what they already planned and plans nothing new. Nobody repeats yesterday, and there is no habit choice.
Nov 2, 2026
SIM Prompt version 6
Never used by a run; version 7 replaced it
- The plaza. Opt-in. Nobody went in the evening unless a plan that day said so.
Nov 2, 2026
From day 2 · April 3
- Isabelle's morning announcement. At most 70 words (yesterday's news is cut short with "and N more"), then one "Did you know" fun fact of up to 15 words about how the island works.
Nov 1, 2026
From day 1 · April 2
- Visit and ask. The action menu says who each is for, and visiting an NPC or a place, or asking a villager, says how to reach them instead.
- A map. Asking Tom Nook or Isabelle gets you an island map, and while you carry it, your plans show the island's layout area by area.
- Axes. Chopping wood with the axe (iron) brings the tree down when it takes the tree's last wood; this run's island has no stone axe. Fruit trees have wood too, and drop their fruit when felled. There is no separate chop_down_tree. This run's villagers started with the axe, so they keep it.
Oct 31, 2026
Day 0 · April 1
- Blank villagers, seed 0, 10 villagers, groq · openai/gpt-oss-20b, prompt version 1 (the original wording).