A spiral is not just high inflation: it is the point where people stop expecting prices to settle and start acting on the expectation that they will keep rising, and that behavior itself pushes prices up further. NationCraft, a free mobile government and economy simulator, builds this mechanism into its monthly economic model: above a set inflation threshold, the simulated economy starts feeding on its own momentum instead of settling back down by itself. The way out in the game is the same lever real central banks reach for: raise the cost of money before the expectation entrenches itself.
This explainer is published by the developer of NationCraft, using the game's own simulation as a worked example of a real economic mechanism. No other games are discussed on this page.
Ordinary high inflation usually has an identifiable cause: demand outrunning supply, a currency losing value, a war disrupting a commodity, a government spending well beyond what it collects. Those pressures can ease. Supply catches up, the disruption passes, spending gets reined in, and inflation drifts back down without anything dramatic happening.
A spiral is a different animal. It becomes self-sustaining because people's expectations of future inflation start changing their present behavior, and that changed behavior is itself inflationary. Workers push for higher wages now because they expect prices to be higher by the time the next raise comes around. Businesses raise prices now because they expect their own costs to rise before they get a chance to adjust again. Savers spend rather than hold cash because money sitting still is expected to be worth less next year. None of those decisions is irrational. Each one is a sensible response to an expectation. But added together, they create exactly the price pressure that the expectation predicted, which confirms the expectation, which keeps the cycle running without needing any new external shock at all.
Economists call the underlying shift "de-anchoring." As long as people broadly expect inflation to return to some stable, familiar rate, their everyday economic decisions, wage asks, pricing, saving versus spending, tend to reinforce that return. Inflation runs a little hot for a while, but the anchor holds, and behavior pulls it back.
The danger is what happens once inflation runs hot for long enough that the anchor itself gives way. Expectations stop pointing back toward "stable" and start pointing toward "more." At that point ordinary, individually reasonable economic behavior stops working against the price rises and starts working with them. This is why a central bank treats a brief spike very differently from the same number sustained for months: a spike that people still expect to pass leaves the anchor in place, while the identical inflation rate held long enough risks breaking it. Once broken, the anchor does not reset on its own. Something has to actively re-anchor expectations, which usually means a central bank convincingly signaling it will make holding money worthwhile again.
NationCraft is a monthly-tick government and economy simulator: you set tax rates, steer a central bank policy rate, buy policies, and watch a national economy evolve one simulated month at a time. Inflation is one of the values the simulation tracks, and it is built to mean-revert, meaning that in an ordinary month it drifts back toward an equilibrium level, and that equilibrium is itself set by the central bank rate the player is holding. Push the rate down and the equilibrium the economy drifts toward runs hotter. Push the rate up and it runs cooler. That single lever is doing real work in the model, not just flavoring a number.
That reversion is the stabilizing force, the in-game version of the anchor holding. Left alone, it would always pull inflation back toward whatever the current rate implies. What makes a spiral possible is a second force layered on top of it. Above 8 percent inflation, the simulation adds an extra pressure term that pushes inflation up simply because it is already elevated: the model's own version of expectations de-anchoring. Below that 8 percent line, that reversion is the dominant force, though spending pressure, debt pressure, and a Phillips-curve term are still acting on inflation at the same time. Above 8 percent, the self-feeding term joins those forces, and if it wins out, inflation keeps climbing on its own even without any new event or policy shock driving it.
The 8 percent line is not a soft description in NationCraft's design notes, it is the literal condition in the simulation code that switches the self-feeding pressure on. Below it, inflation behaves like an ordinary number responding to spending, debt, and unemployment. Cross it and stay there, and the economy starts contributing to its own inflation independent of anything else the player has done that month.
The central bank rate does not just set the equilibrium inflation drifts toward, it also damps how strongly the self-feeding term bites once it is active. A higher rate weakens the extra pressure; the effect is smaller than it would be at a low rate, though the model does not claim a high enough rate eliminates it outright, only that it damps it. That gives tightening real teeth against a spiral already underway, not just against inflation that has not yet crossed the threshold: raising the rate both lowers the level the economy is being pulled toward and weakens the force actively pushing it up.
NationCraft ties this mechanism directly to one of the game's death conditions. If inflation stays above 25 percent for 12 consecutive months, the run ends in hyperinflation: the game's term for a currency collapse severe enough to end a nation's story. That threshold sits well above the 8 percent point where the self-feeding pressure switches on, which is deliberate: crossing 8 percent is a warning that the dynamics have changed, not an immediate loss condition. A player who notices the shift and tightens policy in response can still pull inflation back down before it compounds for a year straight. A player who keeps the rate low, or who lets a run of destabilizing events push inflation up faster than policy responds, can watch the same self-feeding term that switched on at 8 percent carry the number all the way to a death condition.
That gap is where the simulation puts the real decision. Nothing forces a spiral to run all the way to hyperinflation once it starts. It hands the player a lever, the central bank rate, that gets less effective the longer it goes unused and the deeper the self-feeding pressure has already compounded.
In the real world, ending a spiral almost always means a central bank credibly committing to higher rates long enough that expectations re-anchor, which is painful: tighter credit slows hiring and investment on the way down, the same way it does in NationCraft's own model, where a higher rate also drags on growth and raises unemployment while it cools inflation. There is no mechanism, in the game or in the economics it models, for pulling inflation back down for free.
NationCraft compresses that same trade-off into a single dial. Raising the central bank rate lowers the equilibrium inflation is drifting toward and weakens the self-feeding pressure above 8 percent, at the cost of slower growth and higher unemployment while the tightening is in effect. Waiting is not neutral: the longer inflation sits above the threshold, the more months the self-feeding term has to compound before a rate hike catches up to it. The mechanism rewards recognizing the crossing early, which is also the practical lesson underneath the real-world economics: an anchor is much cheaper to defend than it is to rebuild once it has broken.
An inflation spiral is inflation that keeps rising because people expect it to keep rising, not because of a new external cause. Wage demands, pricing decisions, and spending-versus-saving choices shift in response to the expectation itself, adding real inflationary pressure that confirms the expectation that started the cycle.
It is the moment people stop expecting inflation to return to a stable rate and start expecting it to keep climbing. Once that shift happens, everyday economic behavior stops pulling inflation back down and starts pushing it up, which is what separates a temporary spike from a self-sustaining spiral.
Above 8 percent. Below that line, mean reversion toward an equilibrium set by the central bank rate is the dominant force, though deficit spending and debt issuance still push on inflation independently of it. Above 8 percent, an additional pressure term switches on that pushes inflation up simply because it is already elevated.
Yes, on two fronts: it lowers the equilibrium level inflation drifts toward, and it damps the strength of the self-feeding pressure above 8 percent, at the cost of slower growth and higher unemployment while the higher rate is in effect.
If inflation stays above 25 percent for 12 consecutive months, the run ends in NationCraft's hyperinflation death condition, representing a currency collapse severe enough to end the nation's story.
Related: how central bank interest rates work, how countries go bankrupt, games for people who like economics.