ModuleScripts — organizing your code

Your clicker works, but all the logic is stuffed into one Script. It's getting hard to read, and the constants (prices, click values) are buried mid-code. Real Roblox projects split logic into ModuleScripts — separate files that other scripts can load and reuse.

#What a ModuleScript is

A ModuleScript is a file that returns a value when it's loaded. The loading is done by require, and the returned value can be anything: a number, a table of config, a table of functions. Its superpower is that every script that requires it shares the same copy — change one line in the module and every user sees it.

#The simplest module: shared config

Create a ModuleScript in ReplicatedStorage named GameConfig, and put this in it:

local config = {
    coinsPerClick = 1,
    upgradeBaseCost = 25,
    saveInterval = 60,
}

return config

That's it. A ModuleScript is a script that ends in return. Load it anywhere with:

local GameConfig = require(ReplicatedStorage.GameConfig)

print(GameConfig.coinsPerClick) --> 1

Now your prices live in one obvious place. Change upgradeBaseCost and every script that requires it sees the new price — no hunting through a giant file.

#A module of functions

Config is just the start. Modules can hold logic:

local CoinMath = {}

function CoinMath.rewardForClick(multiplier)
    return 1 * multiplier
end

function CoinMath.upgradeCost(baseCost, currentLevel)
    return baseCost * (currentLevel + 1)
end

return CoinMath

local CoinMath = require(ReplicatedStorage.CoinMath)

local reward = CoinMath.rewardForClick(3)
print(reward) --> 3

The empty local CoinMath = {} starts an empty table, functions get attached to it, and the table is returned. This is the standard way to organize: one module per concern. Prices, coin math, UI builders — each gets its own file.

local CoinMath = {}

function CoinMath.double(n)
return n * 2
end

-- your line here

#Refactor your clicker

Move the upgrade prices out of the server Script into GameConfig:

1. Create GameConfig in ReplicatedStorage.
2. At the top of your server Script, add local GameConfig = require(ReplicatedStorage.GameConfig).
3. Replace the hardcoded numbers with GameConfig.coinsPerClick and GameConfig.upgradeBaseCost.

Run it — behavior identical, but now the numbers live in one obvious file. That's refactoring: same behavior, better structure.

#Common mistakes

• Forgetting the return. A ModuleScript with no return gives require nil — and every use of it errors. The return is the whole point.
• Putting side effects in a module. print("loaded") in a module fires once, when first required. Keep modules as pure data/logic.
• Requiring from the wrong place. A server script can't see a module in a client-only location and vice versa. ReplicatedStorage for shared, ServerScriptService for server-only.
• Copy-pasting constants everywhere instead of a module. That's how two halves of your game drift apart.

That closes the Game Systems section: interfaces, economies, and organization. Next section: objects — the parts, players, and effects that bring the world to life.