The game is a toy, but it is not arbitrary. Every relationship in it corresponds to something the Bank of England actually worries about. Here is the whole thing, with the numbers.
You set Bank Rate once a quarter for twenty quarters — five years, the length of a Governor's term. Two numbers judge you: CPI inflation, which the Bank is legally required to hold at 2%, and unemployment, where the target band in the game is a simplification of the Bank's secondary objective to support growth and employment.
The game starts in August 2026 with Bank Rate at 3.75%, inflation at 2.6% and unemployment at 4.9%. You score for quarters where both sit inside their bands — inflation 1–3%, unemployment 3–5% — which is much harder than either alone, because the two pull against each other.
The central tension is the one A.W. Phillips identified in 1958: push unemployment down and inflation tends to rise, squeeze inflation out and unemployment rises. In the game, raising Bank Rate above the neutral rate cools prices and costs jobs; cutting below it does the reverse. There is no setting that improves both at once, only settings that balance them.
The modern refinement matters too. The trade-off is only exploitable in the short run — over time the economy returns toward its natural rate of unemployment (4.4% here) regardless of what you do to prices. Try to hold unemployment permanently below it and you buy nothing but inflation.
A rate change in the game affects the economy the following quarter, never the current one. This is the single most important thing about running monetary policy and the thing players find hardest. The Bank's own estimate is that policy takes somewhere between one and two years to have its full effect, which is why the MPC forecasts rather than reacts. If you wait until inflation is visibly out of control before moving, you are already too late; the medicine arrives after the illness has spread.
Inflation in the game does not revert toward 2%. It reverts toward what people expect, and expectations drift toward whatever inflation has actually been running:
chase = 0.10 + 0.16 × clamp((inflation − 5) / 10, 0, 1)
expectations += chase × (inflation − expectations)
Below about 5%, expectations move slowly — the target still has credibility, and inflation gravitates home on its own. Above it, the coefficient rises and the public starts pricing off what it sees rather than what the Bank promises. That is a wage-price spiral, and it is the mechanism that took UK inflation to 24.2% in 1975. Expectations only re-anchor toward 2% while you are actually holding inflation inside the band, so the way out of a spiral is to get inflation down and keep it down long enough to be believed.
Below zero, falling prices raise the real value of debt and give people a reason to postpone spending. Demand weakens, unemployment climbs, and prices fall further. Japan spent the best part of three decades in that trap, which is why the game's deflation medal is named after it. Deflation is not a safe place to be; it is the other cliff.
There is a neutral rate of interest — economists write it r* — at which policy is neither stimulating nor restraining. It is unobservable in real life, and it is hidden from you in the game too. It also moves: world interest rates wander through the term and drag the UK's neutral rate with them, so the Bank Rate that was right two years ago can be quietly wrong today.
Your read on it comes from the Committee. Each of the eight other members prices their own preferred rate off a Taylor-style rule and the true neutral rate, so when the vote comes back "8 members wanted it far higher", that is the game telling you where neutral has moved. They only advise — the decision is always yours — but ignoring a lopsided vote is usually expensive.
Every quarter carries a chance of an energy shock, in three sizes:
| Tier | Chance | Inflation | Persistence |
|---|---|---|---|
| Minor | ~11% | +0.32pp | Fades in a quarter |
| Major | ~4.7% | +0.75pp | A couple of quarters |
| Crisis | ~1.8% | +3.6pp | Years |
The crisis tier is modelled on 2022, when the invasion of Ukraine pushed UK CPI to 11.1% — its highest in forty years. A crisis in the game can do the same, and the tail keeps feeding inflation long after the headline event. Because it is a supply shock, it is the nastiest thing that can happen to you: it raises inflation and hurts employment simultaneously, so both your targets break at once and the textbook trade-off offers no comfortable answer.
Policy transmission saturates rather than scaling linearly:
squeeze = tanh((rate − neutral) / 4)
inflation += −2.00 × squeeze · unemployment += 0.62 × squeeze
This matters. A linear rule would let a 15% Bank Rate erase a decade of inflation in a single quarter, which is nonsense. With saturation, going to 15% is genuinely powerful but it takes years to break a spiral — and it puts a great many people out of work while it does. That is the actual Volcker experience: the US Federal Reserve took rates above 19% in 1981, broke the back of inflation, and caused the deepest recession since the 1930s doing it.
No fiscal policy, no exchange rate you can see, no quantitative easing, no housing market, no banking system, no distinction between headline and core inflation, and a single interest rate standing in for an entire yield curve. Real forecasting models run to hundreds of equations and still miss. This one has about six, and the point of it is the trade-off, not the forecast.
Play the game →