Live game economies look chaotic from the outside. Underneath they are usually a short list of multipliers applied in a fixed order. The engineering problem is not how to win the game. It is how you encode the sell formula so a client-side tool stays honest after patches, refuses illegal stacks, and does not silently invent value.
This walkthrough uses a compact JavaScript model for a Roblox farming sequel: a power-law weight term, a single mutation seat, a harvest-type keep rule, friend and freshness multipliers, and a hard cap on a luck statistic. The same pattern applies to any domain calculator that must turn a product of rules into a number a user can trust.
Start with an ordered formula
If the UI drives the math, users click every bonus and you overcount. Invert that. Write the formula first, then bind controls to named terms.
value = base
