What Are Upgrades?

Upgrades are the things players buy to make everything go faster. They are the connective tissue between your resources, generators, and prestige layers — the purchases that turn a slow early game into a satisfying avalanche of numbers. A well-designed upgrade tree is what keeps players making meaningful decisions for hours instead of minutes.

In Simple Idle Forge, an upgrade is anything a player can purchase that changes the way the game behaves. That includes:

• Production multipliers — "Double the output of all Mines" or "x3 Gold production globally"
• Flat bonuses — "+100 Gold per second to Lumberjacks" or "+500 base production"
• Percentage boosts — "+50% Iron production" or "+25% to all generators"
• Automation triggers — "Auto-buy Iron Mines whenever you can afford them"
• Feature unlocks — "Reveal the Blacksmith generator" or "Enable the Enchanting tier"
• Resource grants — "Receive 10,000 Gold immediately" as a one-time care package

Upgrades can be one-time purchases (buy it once and the effect is permanent) or repeatable (buy it as many times as you can afford, with costs scaling each time). A one-time upgrade like "Double Miners" is a milestone moment. A repeatable upgrade like "Mining Efficiency +1%" is a steady drip of power that scales with your economy.

Here are some examples from the four included demo games:

The Upgrade Forge is the third forge in the chain, after Resources and Generators. It knows about both of them — it pulls resource codes for costs (what the upgrade costs to buy) and generator codes for targets (what the upgrade affects). By the time you open the Upgrade Forge, you should already have your resources and generators defined so the wizard can connect everything together.

Opening the Upgrade Forge

Open the Upgrade Forge wizard from the Unity menu bar:

Window → Living Failure → Simple Idle Forge → Upgrade Forge

The wizard window opens with a tab bar across the top showing all five steps. You can click any tab to jump directly to that step, and the wizard validates your work in real time — if something needs attention, you will see it immediately. The Upgrade Forge is the third forge in the menu (after Resource Forge and Generator Forge), reflecting the natural order of building an idle game: define your currencies first, then your producers, then the boosts that accelerate them.

Linking Databases

The Upgrade Forge links to two types of databases: resource databases and generator databases. This is because upgrades sit at the intersection of your game's economy — they cost resources to buy and they modify generators (or resources, or the whole game) when purchased.

Why Resource Databases?

Every upgrade has a cost. That cost is expressed in resource codes — "costs 1,000 GOLD" or "costs 500 IRON and 200 WOOD". The Upgrade Forge needs access to your resource databases so that when you set up costs, you get a dropdown of valid resource codes instead of typing them manually. This eliminates typos and ensures every cost references a real resource that exists in your game.

Resource databases are also needed for the ResourceGrant effect type. When an upgrade grants a one-time dump of resources to the player, the target code is a resource code. And for upgrades that target a specific resource (like "+50% Gold production"), the target code dropdown is populated from your linked resource databases.

Why Generator Databases?

Most upgrades in an idle game affect a specific generator: "Double the output of Mines", "Automate Lumberjacks", "Unlock the Blacksmith". The Upgrade Forge needs your generator databases so it can populate the target code dropdown with valid generator codes. When you set an upgrade's target type to Generator and pick a target code, you are telling the system exactly which producer this upgrade modifies.

Generator databases also feed into the prerequisites system. If you want an upgrade to require "Mines at level 10 before it becomes available", the wizard needs to know what generators exist so it can offer them in the condition dropdown.

Linking in the Wizard

Step 1 of the wizard has two sections for linking databases: one for resource databases and one for generator databases. Each section shows a list where you can drag and drop databases from your project, or click the add button to browse. The wizard validates each database you add — it must implement the correct data source interface. Duplicate databases are automatically detected and flagged.

You can link multiple resource databases and multiple generator databases. This is useful if your game separates resources into different databases (one for currencies, one for materials, one for prestige currencies) or generators into different tiers. The wizard merges all codes from all linked databases into a single unified dropdown, so you always see every valid code regardless of which database it lives in.

The 5 Steps

The Upgrade Forge follows the same five-step wizard pattern as every forge in the toolkit. You work through them in order (though you can jump between tabs at any time), and each step builds on the one before it.

The Builder in Detail

Step 3 is where you spend most of your time in the Upgrade Forge. The split-panel layout gives you a master list on the left and a full detail editor on the right. Here is everything you can configure on each upgrade entry, in the order it appears in the editor.

Identity

Every upgrade starts with four identity fields:

• Code — A unique string identifier used in code and cross-references. Must be a valid identifier (letters, numbers, underscores). Examples: MINE_BOOST, AUTO_IRON, GLOBAL_SPEED_UP. This becomes an entry in the generated enum.
• Display Name — The human-readable name shown to players. "Improved Mining", "Iron Automation", "Time Warp".
• Description — A text description of what the upgrade does. This is what players read in your upgrade shop: "Doubles the output of all Iron Mines" or "Automatically purchases Lumberjacks whenever you can afford them".
• Icon — An optional sprite reference for your UI.

Costs

Upgrades can cost multiple resources. Each cost entry has four fields:

• Resource Code — A dropdown populated from your linked resource databases. Pick which resource this cost is paid in (GOLD, IRON, GEMS, etc.).
• Base Cost — The starting price. For one-time upgrades, this is the flat price. For repeatable upgrades, this is the price of the first purchase.
• Scaling Type — How the cost changes with each purchase. The same five formulas available in the Generator Forge:

• Scaling Factor — The number used in the formula. For Exponential, 1.15 is gentle, 1.5 is standard, 2.0 is steep. For Linear, this is the flat amount added per purchase.

For one-time upgrades (maxPurchases = 1), scaling does not matter since the upgrade is only ever bought once. But for repeatable upgrades, the scaling formula determines how quickly the price ramps up. The wizard provides preset buttons for common configurations:

• Exponential presets: Gentle (1.07), Standard (1.15), Steep (1.5), Aggressive (2.0)
• Linear presets: +10, +baseCost
• Polynomial presets: Quadratic (2.0), Sub-Quadratic (1.5), Cubic (3.0)
• Logarithmic presets: Gentle (0.5), Standard (1.0), Steep (2.0)

Each cost entry also includes a formula display in a help box that shows the exact formula being used, and an interactive cost preview slider (range 1–200) that lets you see the cost at any purchase count. The preview shows both the cost at the selected level and the cumulative total cost to reach that level. This lets you tune your economy before generating anything — if level 50 of a repeatable upgrade costs 10 trillion Gold and your players only have millions, you know the scaling factor needs to come down.

Max Purchases (Limits)

This single field controls whether an upgrade is one-time or repeatable:

• 1 — One-time purchase. The player buys it once, the effect applies permanently, and it disappears from the shop (or shows as "Purchased"). This is the most common type for named upgrades like "Double Miners" or "Unlock Blacksmith".
• 0 — Unlimited repeatable. The player can buy it as many times as they can afford. Each purchase applies the effect again (stacking additively or multiplicatively depending on the effect type). Costs scale with each purchase according to the scaling formula. This is the bread and butter of idle game progression — upgrades like "Mining Efficiency +1%" that the player buys dozens or hundreds of times.
• Any other number — Limited repeatable. The player can buy it up to that many times. For example, maxPurchases = 5 means the upgrade can be purchased five times before it is fully exhausted. Useful for powerful upgrades you want available in limited quantities.

The Six Effect Types

The effect is the core of every upgrade — it defines what actually happens when a player buys it. Simple Idle Forge provides six effect types that cover every scenario an idle game needs. Each effect type combines with a target type and target code to determine exactly what gets modified and how.

Target Type and Target Code

Before diving into the effects, understand how targeting works. Every upgrade has a target type that determines the scope of its effect:

• Generator — The upgrade affects a single, specific generator. Set the target code to the generator's code (e.g., IRON_MINE). The effect applies only to that generator's production.
• Resource — The upgrade affects a single, specific resource. Set the target code to the resource's code (e.g., GOLD). The effect applies to all production of that resource, regardless of which generator produces it.
• Global — The upgrade affects everything. Leave the target code blank. The effect applies universally to all generators and all resources across your entire game. Use this for powerful, game-wide boosts.

Now, the six effect types:

1. Multiply

Multiplies the target's output by the effect value. An effect value of 2 means "double the production". An effect value of 3 means "triple it". This is the most dramatic and satisfying upgrade type for players — buying a x2 multiplier and watching all your numbers instantly double is the core dopamine hit of idle games.

Example: Target Type = Generator, Target Code = IRON_MINE, Effect Value = 2. Result: Iron Mine production is multiplied by 2.

Stacking behavior: Each Multiply bonus is applied independently. If you have two x2 multipliers targeting the same generator, the total multiplier is 2 × 2 = 4, not 2 + 2 = 4. This means stacking multipliers gets very powerful very fast — three x2 multipliers give x8 total. Design accordingly.

2. AddFlat

Adds a flat amount to the target's base production. An effect value of 100 means "+100 per second" added to the base before any multipliers apply. This is less flashy than Multiply but very important for early-game progression when multiplying a tiny base does not move the needle much.

Example: Target Type = Generator, Target Code = LUMBERJACK, Effect Value = 50. Result: Every Lumberjack produces 50 more per second on top of its base production.

Stacking behavior: All AddFlat bonuses sum together. If you have +100 and +50 flat bonuses targeting the same generator, the total flat bonus is 150. Flat bonuses are added to the base value before percentage and multiply bonuses are applied, which means they get amplified by everything that comes after them in the stacking pipeline.

3. AddPercent

Adds a percentage bonus to the target. An effect value of 0.5 means "+50% production". This is applied after flat bonuses but before multipliers. AddPercent is the middle ground between the dramatic power of Multiply and the steady consistency of AddFlat.

Example: Target Type = Resource, Target Code = GOLD, Effect Value = 0.25. Result: All Gold production is increased by 25%.

Stacking behavior: All AddPercent bonuses sum together, then apply as a single multiplier. If you have +50% and +30% percentage bonuses, the combined effect is ×(1 + 0.5 + 0.3) = ×1.8, not ×1.5 × 1.3 = ×1.95. This additive stacking means percentage bonuses become less impactful as you accumulate more of them, which is a natural balancing mechanism. Your tenth +10% upgrade is less exciting than your first.

4. Unlock

Reveals a locked generator or feature. The effect value is not used (typically set to 1). This upgrade type changes the game's structure rather than its numbers — it makes something available that was not available before.

Example: Target Type = Generator, Target Code = BLACKSMITH, Effect Value = 1. Result: The Blacksmith generator becomes available for purchase. Before this upgrade, the Blacksmith is hidden or greyed out in your UI.

Design note: Unlock upgrades work best as one-time purchases that gate progression. "Spend 10,000 Gold to unlock the Enchanting tier" is a satisfying milestone that gives the player a clear goal to work toward. You control the gating entirely through the unlock upgrade's cost and prerequisites.

5. Automate

Enables automatic purchasing for a specific generator. Once purchased, the auto-purchase system will buy levels of the target generator whenever the player can afford them — no manual clicking required. This is one of the most satisfying upgrade types in idle games because it fundamentally changes how the player interacts with that generator.

Example: Target Type = Generator, Target Code = IRON_MINE, Effect Value = 1. Result: Iron Mines are now auto-purchased. The auto-purchase system buys one level whenever the player has enough resources.

How it works: When an Automate upgrade is purchased, the runtime automatically registers the target generator with the auto-purchase system. You do not need to write any code or configure anything else. The auto-purchase system supports four strategies (Cheapest first, Most Expensive first, Round Robin, or Disabled), and the player or your UI can switch between them at any time. But the key insight is that Automate upgrades are the opt-in mechanism — a generator only gets auto-purchased if the player has bought the corresponding Automate upgrade for it.

6. ResourceGrant

Gives the player a one-time dump of a resource when purchased. The target code is the resource code (not a generator code), and the effect value is the amount granted. This is useful for "care package" upgrades that give stuck players a boost, or for premium/prestige-tier purchases that reward the player with a large infusion of a specific currency.

Example: Target Type = Resource, Target Code = GOLD, Effect Value = 50000. Result: The player receives 50,000 Gold immediately when they buy this upgrade.

Design note: ResourceGrant upgrades are most useful as one-time purchases. Making them repeatable can trivialize your economy if the grant amount is large. But a repeatable ResourceGrant with exponentially scaling costs can work as an "exchange" mechanic — "Spend Gems to get Gold" where the Gem cost increases each time.

Quick Presets in the Wizard

The Upgrade Forge builder provides six quick preset buttons that configure the effect section with a single click. These are starting points — you can modify any field after applying a preset:

Effect Preview

Below the effect configuration, the wizard shows a live preview in a help box. This preview includes the formula description ("Multiplies IRON_MINE production by 2.00"), the stacking behavior for repeatable upgrades ("At 5 purchases: total multiplier = 32.00"), and a description of how this effect interacts with the bonus stacking pipeline. For repeatable upgrades, an interactive slider lets you see how the effect compounds at different purchase counts — so you can verify that 10 purchases of a +10% AddPercent upgrade gives +100% total (not +159% like it would with multiplicative stacking).

Dynamic Properties

Below the effect section, foldouts for your custom dynamic properties appear — categories, flags, numerics, and text fields, exactly as you defined them in Step 2. These are single-level properties that appear on every upgrade entry. Use them for anything your game needs that the built-in fields do not cover: visual tier indicators, sort priorities, flavor text, UI hints, unlock animations, sound effect keys, or any other metadata your upgrade shop UI needs.

How Bonus Stacking Works

Understanding how bonuses stack is critical to designing a balanced idle game economy. Simple Idle Forge uses a single, transparent stacking pipeline for all bonuses in the game — from upgrades, prestige layers, achievements, milestones, and temporary buffs. Everything feeds into the same formula, in the same order, every time. No hidden interactions, no mysterious order-of-operations bugs.

The pipeline is:

finalValue = (base + sumOfAllFlatBonuses) × (1 + sumOfAllPercentBonuses) × multiplier1 × multiplier2 × ...

In plain English:

A Concrete Example

Let's trace through a real scenario. You have an Iron Mine with base production of 10 per second, and the following bonuses targeting it:

• Upgrade "Better Pickaxes": AddFlat +5
• Upgrade "Mining Efficiency": AddPercent +50% (effect value 0.5)
• Upgrade "Double Miners": Multiply x2

Here is the pipeline in action:

The final production is 45 per second, up from 10. Notice how the flat bonus of +5 ends up contributing much more than 5 to the final result — it gets amplified by both the percentage bonus and the multiplier. This is why AddFlat upgrades are more powerful than they might seem at first glance, and why the order of the pipeline matters so much.

This stacking pipeline is the same one used by prestige permanent bonuses, milestone rewards, achievement rewards, and temporary buffs. Everything in the game that modifies production feeds into the same formula, so you always know exactly what the final number will be.

Prerequisites

Prerequisites are conditions that must be met before an upgrade becomes available for purchase. They let you create a progression tree where powerful upgrades are gated behind earlier achievements, resource thresholds, or generator milestones. A game without prerequisites is a game where the player buys the strongest upgrade first and skips everything else. Prerequisites force meaningful progression.

Each prerequisite has four fields:

• Condition Type — What kind of check to perform. The available types are:

• Target Code — The specific resource, generator, upgrade, or milestone code to check against. The wizard provides context-aware dropdowns: when the condition type is ResourceAmount, you see resource codes from your linked databases. When it is GeneratorLevel, you see generator codes. When it is UpgradePurchased, you see codes of other upgrades in the current wizard (excluding the upgrade you are editing, to prevent self-referencing).
• Comparison — The comparison operator: Equals, Not Equals, Greater Than, Less Than, Greater or Equal, Less or Equal.
• Value — The threshold to compare against. For "requires Gold >= 5000", the value is 5000.

An upgrade can have multiple prerequisites. All of them must be satisfied simultaneously (they are ANDed together). For example, "Warrior Training" might require:

• MINE level >= 10
• GOLD >= 5000
• BASIC_MINING_BOOST purchased (UpgradePurchased, value >= 1)

All three conditions must be true before Warrior Training appears in the upgrade shop.

The wizard shows a human-readable summary below each prerequisite entry: "Requires: MINE Level >= 10" or "Requires: GOLD Amount >= 5.0K". This makes it easy to verify at a glance that your prerequisites make sense without mentally parsing condition types and codes.

Tips for Upgrade Design

Upgrades are the levers that control your game's pacing. Get them right and your idle game sings. Get them wrong and players either stall out (upgrades are too expensive) or blast through everything in minutes (upgrades are too powerful). Here are design principles drawn from the best idle games ever made:

Mix One-Time and Repeatable Upgrades

One-time upgrades are milestones — they feel like events. "You just unlocked Double Mining!" is a moment the player remembers. Repeatable upgrades are steady progression — they feel like investment. "Mining Efficiency is now level 47" is a number the player watches grow. The best idle games use both: one-time upgrades for dramatic power spikes and unlock moments, repeatable upgrades for the steady drip of incremental improvement between those spikes.

A good ratio to start with: about 60% one-time upgrades and 40% repeatable. The one-time upgrades provide structure and goal posts. The repeatable upgrades fill in the gaps between them.

Automation Upgrades Feel Great as Milestone Rewards

There is a reason every successful idle game gates automation behind progression. When a player manually buys 50 levels of Iron Mine and then purchases "Auto Iron Mine", it feels like a reward for their effort. The manual clicking was the journey; the automation is the destination. Do not give automation upgrades away cheaply or early. Make them something the player earns after meaningfully engaging with the generator they automate.

A common pattern: place the Automate upgrade for each generator at roughly the same progression point where that generator starts to feel tedious to manage manually. If a player has been clicking "Buy Lumberjack" for 15 minutes, the Automate Lumberjack upgrade should appear right around that 15-minute mark. The game reads the player's mind: "This is getting repetitive" — and immediately offers the solution.

Use Prerequisites to Gate Powerful Upgrades

An idle game without gating is an idle game where the player buys the best thing immediately. Prerequisites force progression through your intended path. The player cannot buy "x3 Global Production" until they have bought "x2 Mine Production" and reached generator level 25. This creates a breadcrumb trail of goals that keeps the player engaged for hours instead of minutes.

Layer your prerequisites: the first tier of upgrades has no prerequisites (available immediately). The second tier requires first-tier upgrades or low generator levels. The third tier requires second-tier upgrades and medium resource thresholds. This creates a cascading unlock system where every purchase brings new options into view.

ResourceGrant Upgrades Work as Care Packages

Every idle game has moments where the player gets stuck. Maybe they are saving for an expensive generator but the progress is painfully slow. A one-time ResourceGrant upgrade — "Receive 50,000 Gold" — acts as a release valve. It gives the stuck player a burst of resources to push through the bottleneck. Place these strategically at points in your progression where you know players might stall, priced just below the "frustration threshold".

ResourceGrant upgrades are also perfect for premium/prestige mechanics: "Spend 10 Gems to receive 100,000 Gold" where Gems are a premium currency. This gives Gems a concrete value without breaking the core economy, because you control exactly how much Gold each Gem purchases.

Think About Reset Interactions

If your game has a prestige system (and most idle games should), think about which upgrades survive a reset and which get wiped. The Prestige Forge controls this through reset rules, but you should design your upgrades with resets in mind from the start. Automation upgrades that survive prestige make each subsequent run much smoother. Production multipliers that reset create a reason to buy them again each run, which drives engagement with the upgrade shop.

A common pattern: early upgrades reset on prestige (so the player re-buys them each run, faster each time thanks to permanent bonuses). Late-game upgrades survive prestige (so the player does not feel punished for investing in expensive purchases). This creates a satisfying loop where each prestige run starts easy, accelerates through the upgrade tree faster than before, and pushes further into new territory.

Preview Your Economy Before Generating

The Upgrade Forge's cost preview slider and effect preview are not just convenience features — they are design tools. Before you click Generate, scroll through your upgrades and check: Is the 20th purchase of Mining Efficiency still affordable when the player has 1 billion Gold? Does the x2 Global Production upgrade cost enough to feel like a meaningful investment? Are your Automate upgrades priced at the right progression point? The preview tools give you these answers before you leave the wizard.