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12 Idle Game Achievement Systems Worth Stealing, From Milk to Shadow Achievements

Idle game achievements done well: 12 real systems, from Cookie Clicker's milk and shadow achievements to Antimatter Dimensions' multiplier, with the numbers.

Developer guideMaintained by Maxwell PrehodaHow we choose

In most genres achievements are a badge. In idle games they are often part of the economy: Cookie Clicker turns each one into milk that multiplies production, Antimatter Dimensions multiplies everything by 1.03 per achievement and 1.25 per completed row, and Trimps gives percentage attack. Others stay purely cosmetic on purpose, as secrets, jokes or long-haul challenges.

The 12 designs below each show one decision you have to make: rewarded or cosmetic, visible or secret, how many, and named how. Numbers come from each game's wiki, its public source or its Steam store data as of November 2026.

02

Shadow achievements: best for unfair or absurd goals that should not be required

Platform: Cosmetic tier. Cookie Clicker has 17

Cookie Clicker's solution to the problem above is a separate tier. Its 17 shadow achievements are 'unfair or difficult-to-attain achievements that are purely cosmetic,' per the wiki: they give no milk and do not count toward completion. Examples: 'Cheated cookies taste awful' (hack in cookies), 'Third-party' (use an add-on), 'Just plain lucky' (a one-in-a-million chance every second), and 'So much to do so much to see' (keep a save for at least a year).

Shadow achievements let you acknowledge cheaters, modders and the extremely patient without punishing everyone else. Nobody has to grind a year to stay competitive.

Copy the split: rewarded achievements for fair play, a cosmetic shelf for everything else.

Watch out for: Label the tier clearly in the UI. Players who chase completion percentages need to know which achievements count.

03

Antimatter Dimensions: best for a global multiplier with row bonuses

Platform: Browser, Steam, Mobile · free

Antimatter Dimensions lays achievements out in rows of eight. Its achievement code computes the bonus as 1.25^(completed rows) × 1.03^(achievements), raised to a further exponent later in the game, and many individual achievements carry their own reward on top.

The row bonus is the clever part. A 25% jump for finishing a row gives players a reason to go back for the one achievement they skipped, which turns the grid into a checklist with a payoff.

Copy the structure if your game has distinct stages: one row per stage, a bonus for clearing it. The Steam version lists 100 Steam achievements, a curated subset.

Watch out for: Compound bonuses snowball. At 1.03 per achievement, 100 achievements is about a 19x multiplier before row bonuses; balance later content with that in mind.

Read the profile →

04

Secret achievements: best for rewarding curiosity about the interface

Platform: Antimatter Dimensions secret-achievements.js

Antimatter Dimensions keeps a separate set of secret achievements in secret-achievements.js. 'The first one's always free' is earned by clicking the achievement itself. 'Stop right there criminal scum!' fires when you open the browser console. '30 Lives' wants the Konami code, and 'Real news' asks you to click a news ticker message that does something.

These reward poking at the game rather than playing it well. They spread on forums because they are fun to discover and to share, which is free word of mouth.

Copy the spirit with a handful of secrets tied to your own UI and jokes.

Watch out for: Secrets that grant power get spoiled instantly and then feel mandatory. Keep secret achievements cosmetic, or give them trivial rewards.

05

Kittens Game: best for a harder star version of the same goal

Platform: Browser, Mobile · free

Some Kittens Game achievements have a second tier, a star, defined by a starCondition in achievements.js. 'Jupiter Ascending' is 'Get to space on the first year'; its star version adds 'without using Chronospheres.' 'Serenity' has a star for 'Have 1000 kittens without losing any of them.'

One achievement, two difficulties. Casual players get the normal version on the way; challenge runners get a harder goal without cluttering the list with near-duplicates.

The game also has hidden ones, including 'The Elder Legacy,' whose condition in the code checks for January 2017, a time-limited nod to long-time players.

Watch out for: Time-limited achievements cannot be earned later, which frustrates completionists on Steam. If you add one, make it hidden and cosmetic.

Read the profile →

06

Trimps: best for tiered achievements worth combat power

Platform: Browser · free

Trimps grades achievements by tier, and each tier adds a percentage to your Trimps' attack. The values in config.js run from 0.3% at the lowest tier through 1%, 2.5%, 5% and up to 3,000% at the top, with a code comment noting a total of 4,448% after version 4.6.

The bonus appears in the attack breakdown as its own 'Achievements' line, so players can see exactly what their collection is worth. Late tiers are huge, which keeps achievements relevant deep into the game.

Copy the escalating tiers if your game runs for months: early achievements are a nudge, late ones a real power spike.

Watch out for: Large late bonuses can become required for progress. Check that a player who skips optional achievements can still clear your main content.

Read the profile →

07

Revolution Idle: best for Steam achievement hunters who want volume

Platform: Steam, Mobile · free-to-play

Revolution Idle lists 675 achievements on its Steam page, with highlighted ones such as 'A million', 'First Ascension', 'RGB' and 'Let's Prestige'. It is free to play and 87% positive on Steam.

A large list suits a game built on many prestige layers: each layer and threshold becomes a milestone, and achievement hunters, who track their totals on sites like Exophase, actively look for games like this.

Pick volume if your game naturally has hundreds of thresholds, and name them so each one tells the player where they are.

Watch out for: Hundreds of numeric milestones can feel like noise. Highlight a few meaningful ones on your store page, as Steam lets you, so the list does not read as padding.

Read the profile →

08

Unnamed Space Idle: best for number ladders named in the game's notation

Platform: Browser, Steam · free

Unnamed Space Idle has 317 Steam achievements, and its highlighted ones form a ladder: 'Kill 100', 'Kill 10,000', 'Kill 5e5', 'Kill 2e6', per its Steam page. The names switch to scientific notation as the numbers grow, matching how the game itself displays values.

Ladders are the cheapest achievements to design and they work: each one is a visible next step. Using the game's own notation keeps them readable at large numbers.

Copy the ladder for your core verbs (kills, clicks, resources), spaced by orders of magnitude.

Watch out for: Space the rungs by time, not just by number. If two rungs unlock seconds apart, merge them.

Read the profile →

09

Nodebuster: best for a short game with a completable list

Platform: Steam · paid

Nodebuster has just 13 Steam achievements, with names like 'Awakened', 'Routine', 'Milestones' and 'Crypto Mine', per its Steam page. The store describes it as 'a short, experimental incremental game,' and the list is sized to match.

A small list that a normal playthrough can finish gives players a satisfying 100% at the end of a short game, and a reason to replay for the last one or two.

Copy it if your game is a few hours long. Aim for one achievement per meaningful stage plus a couple of optional challenges.

Watch out for: With only a dozen achievements, each one is noticed. Make sure none depends on luck or a bug-prone edge case.

Read the profile →

10

Rusty's Retirement: best for achievement names with personality

Platform: Steam · paid

Rusty's Retirement lists 71 Steam achievements, and its highlighted names include 'This is nice!' and 'This is not so nice.', alongside 'A New Crop!' and 'Green Thumb', per its Steam page.

Names are the cheapest way to add character. A paired 'nice' and 'not so nice' tells you about the game's tone before you read a single description, and players screenshot and share funny achievement pops.

Write names in your game's voice, then make the description say plainly what to do.

Watch out for: Jokey names hide what the achievement wants. Keep descriptions literal so players can actually work toward them.

Read the profile →

11

Bongo Cat: best for idle companions that count real activity

Platform: Steam · free

Bongo Cat has 28 Steam achievements, with highlighted ones 'Bongo Beat 1', 'Bongo Beat 10', 'Bongo Beat 100' and 'Bongo Beat 1.000', per its Steam page. The cat drums whenever you press a key, so the ladder counts your everyday typing.

For a desktop companion, achievements are the progression: they mark how long the cat has been with you. A simple log-scale ladder fits that perfectly.

Copy it for any game that runs beside other work: reward time spent with the game, not attention paid to it.

Watch out for: Counting real input can raise privacy questions. Count events, never content, and say so on your store page.

Read the profile →

12 · Ours

Mushies!: best for small permanent bonuses in a cozy clicker

Platform: Browser, Steam

Mushies! is the cozy mushroom-village clicker made by this site's maintainer, built in Godot, so read this as a case study. Its current build has 18 achievements in four groups, Discovery, Collection, Clicking and Special, and each grants a small permanent bonus: most add 0.5% to production or click power, and a few add 1% or 2%.

Small bonuses keep achievements rewarding without making them mandatory, a middle ground between Cookie Clicker's milk and purely cosmetic badges.

One lesson from its code: two rewards were once paid in a resource that did not exist, and the game silently discarded them until a 2026 fix converted them into real production bonuses.

Watch out for: Mushies is still in development, so its list may change before release. Write a test that unlocks every achievement and checks that its reward actually changes a number.

Read the profile →Free browser demo ↗

How to choose an achievement design

Answer three questions before writing the first one.

01

Match the reward to your economy

If you want every player to care, reward achievements through one clear resource, like Cookie Clicker's milk or Antimatter Dimensions' multiplier. If you want them optional, keep bonuses tiny, as Mushies does, or purely cosmetic. Never reward luck-based or tedious achievements with power; give those a cosmetic tier like Cookie Clicker's shadow achievements.

02

Match the count to your length

Steam lists range from 13 for Nodebuster, a short game, to 637 for Cookie Clicker and 675 for Revolution Idle, both built to be played for months. A rough guide: one or two per hour of intended play for short games, and number ladders plus per-layer milestones for long ones.

03

Match the visibility to the goal

Visible achievements are goals, so show them early and make descriptions literal. Secret achievements are discoveries, so tie them to your interface and jokes, as Antimatter Dimensions does. Harder versions of the same goal can sit behind a star, as in Kittens Game, rather than as separate entries.

Draft your first twenty tonight

Open a sheet with four columns: name, condition, reward and roughly when a player will earn it. Write five ladder achievements for your main verb, one per stage of your game, three challenges and two secrets. Then check the timing column: if two land within a minute of each other, merge them.

Once your game is playable, list it on IncrementalGames.org for free; completionists browse by depth and length. If you want more of them at launch, the optional Get featured placement adds a labelled Featured card on the home page, game pages and best-of lists.

List your game free →

Common questions

Should achievements give bonuses in an idle game?

They can, and many of the best known do. Cookie Clicker's achievements grant 4% milk each, which boosts production through kitten upgrades; Antimatter Dimensions multiplies production by 1.03 per achievement. Keep luck-based or extreme ones cosmetic so nothing unfair becomes mandatory.

What are shadow achievements in Cookie Clicker?

A set of 17 purely cosmetic achievements for unfair or extreme feats, such as cheating in cookies, using an add-on or a one-in-a-million random chance. They give no milk and do not count toward completion.

How many achievements should an idle game have?

Match it to length. Nodebuster, a short game, has 13 on Steam; Antimatter Dimensions has 100; Cookie Clicker 637 and Revolution Idle 675. Short games benefit from a completable list; long games can use number ladders and per-layer milestones.

How do achievement multipliers work in Antimatter Dimensions?

Its code multiplies 1.25 for each completed row of eight by 1.03 for each achievement, then raises the result to an exponent that grows later in the game. Many achievements also have individual rewards.

Sources