One purchase can change another factory’s price
Factory inflation applies across buildings, so the next price matters more than a price remembered from the start of the run. The official controls let you hold Ctrl, or Cmd on Mac, to buy multiple factories. Use a single purchase when you need to inspect the next price before committing more money. Official economy and controls.
How long until the next factory?
Use max(0, price − current balance) ÷ income per second. Price, balance and income must refer to the same currency. The result is a saving-time estimate with unchanged income and no intervening spending.
| Example inputs | Calculation | Meaning |
|---|---|---|
| Price 3,000; balance 1,000; income 50 per second | (3,000 − 1,000) ÷ 50 = 40 seconds | You need another 2,000, not the full purchase price. |
| The same price; balance 3,000 | No shortfall: 0 seconds | The price is already covered; this says nothing about whether the factory is a good combat choice. |
| A positive shortfall; income 0 | No finite saving time at that rate | Waiting alone cannot close the shortfall under the assumed inputs. |
These are worked examples, not measured game prices. Use the saving-time calculator with your own numbers. If the next factory changes the price or your income changes, enter the new values.
A combat factory produces fighting units; its purchase price divided by your existing income is not its investment return. A payback calculation would require the additional income attributable to that factory.
Sunflowers replace Briars as resource producers
The September 9 update describes Sunflowers as resource producers replacing Briars. This is a different role from sending another fighting unit to the frontline. If an older guide tells you to build Briars, that name and role may no longer match the updated roster. Official Sunflower change.
For the saving-time calculation, use the income currently displayed by your build after its production changes. Do not enter a unit’s damage or its factory’s unit-production rate as currency income. The announcement gives no Sunflower income amount or purchase-cost formula, so it does not establish a payback time or an optimal producer-to-combat ratio.
Coins, interest and skipped levels
Base-victory coin rewards depend on which levels you actually play. Interest has an earning window before the money is spent. A historical prototype discussion raised both issues when a restart skipped early levels; see the coin-versus-interest comparison for the conditions. No fixed “+3k” income amount or universal purchase priority is assumed here.
Purge and death are not interchangeable instructions
The developer recommends periodically purging because building prices rise. The public description does not specify a separate Purge button location, a refund formula, a complete retained-resource list or a trigger price. That description alone is insufficient for step-by-step reset instructions.
The explicitly documented death result is different information: upgrades and war points remain, factories are lost, and the run returns to an earlier level. See what persists after death.
Do not reset because the calculator shows a long wait. It measures affordability only. If the action in your build does not state what will be lost, keep the run intact and use the developer’s game page to find the appropriate support route.