Tools
Because marking an achievement “Hidden” in Steamworks does not hide that it exists. It hides the achievement from a player’s Community profile until they unlock it. The achievement itself — its internal name, its display name, its description — still lives in your app’s public achievement schema, and third-party aggregators read that schema the moment your app becomes community-visible.
This week that gap produced a large-scale leak: achievement lists for hundreds of upcoming games, including unannounced titles, surfaced on tracking sites. For anyone shipping a game with a story, this is a design decision you are making whether or not you know it.
What the Steamworks documentation actually says
Valve’s own achievement documentation is unusually direct about the scope of the Hidden flag:
“Hidden? — If true, a ‘hidden’ achievement does not show up on a user’s Community page (at all) until they have achieved it.”
Read that carefully. The subject is a user’s Community page. It is a display rule for player profiles. It is not an access control on the achievement data.
The same page adds the condition that matters for timing:
“Your achievements will not be shown until your app is somewhat visible to the community.”
So the exposure window opens when your app becomes community-visible — which for most games means when the store page goes up, long before release.
The chain, step by step
| Step | What happens |
|---|---|
| 1 | You configure achievements in the Steamworks control panel, with names and descriptions |
| 2 | Your app becomes community-visible — typically at store page publication |
| 3 | The achievement schema becomes readable through Steam’s public interfaces |
| 4 | Aggregators poll those interfaces on a schedule and record what they find |
| 5 | Your boss names, ending titles and secret characters are now a public diff |
Nothing here is a breach. No one hacked anything. The data was published by the developer, through a checkbox that solved a different problem.
What developers can actually do
Write achievement text as if it ships publicly on day one, because it does
The reliable fix is editorial, not technical. “Defeat the Ashen King in under three minutes” leaks a boss, an act structure and a difficulty tier. “Complete Chapter 4 without taking damage” leaks nothing and still tells the player what to do once they are there.
Add achievements late
Achievements do not have to be configured months before launch. If the list does not exist in the control panel, there is nothing to poll. Valheim shipped its first achievement list with version 1.0 in September 2026 after five and a half years in Early Access, which is a defensible pattern for any game whose content is still moving.
Use placeholder names, then rename
The internal API name is fixed once set, but the display name and description are editable and localisable. Configuring the plumbing under neutral strings and writing the real text near launch gives you the integration time without the exposure — though anyone who was already watching will see the rename.
Know the 100-achievement default
Valve limits new games to 100 achievements initially; more become available once the app reaches the Profile Features threshold. That ceiling is worth planning around before you design a 250-achievement completion structure.
The honest caveat: none of this is a security boundary
There is no Steamworks setting that makes a configured achievement invisible to a determined observer. Global achievement statistics are published by design — Valve documents a public page showing the percentage of players who have unlocked each achievement, ordered most common to rarest. That feature is the point of achievements, and it is incompatible with secrecy.
Treat your achievement list as marketing copy that ships early. Anything you cannot afford to have read by a stranger before launch should not be in it.
Three things this does not mean
It does not mean aggregators did something wrong. They read public interfaces. The exposure decision was made upstream.
It does not mean you should skip achievements. They are a completion and retention feature with measurable effect, and the cost of leaking a few nouns is usually smaller than the benefit.
It does not mean hidden achievements are useless. They still do their job on the player’s profile, which is where most players actually encounter spoilers. The flag is fine. The expectation was wrong.
Frequently asked questions
How did Steam achievements leak for unreleased games?
Achievement data becomes readable through Steam’s public interfaces once an app is community-visible, which usually happens when the store page goes live. Tracking sites poll those interfaces and publish what appears.
Does marking a Steam achievement hidden stop spoilers?
Only on player Community profiles. Valve’s documentation says a hidden achievement does not show up on a user’s Community page until they have achieved it. It does not remove the achievement from the app’s public schema.
Can developers stop Steam achievements from leaking?
Not with a setting. The practical options are to write achievement text that reveals nothing, to configure achievements late, or to use placeholder strings and rename them close to launch.
How many achievements can a Steam game have?
New games are limited to 100 by default. More become available once the app reaches the threshold for Profile Features.
Are Steam achievement statistics public?
Yes. Valve documents a global achievement statistics page for each game showing the percentage of players who unlocked each achievement, ordered from most common to rarest.
When should an indie developer add achievements?
Late enough that the content is settled. If the design is still moving, configuring achievements early publishes decisions you have not finished making.
Sources and citation
- Valve Steamworks documentation, Stats and Achievements — Hidden flag, community visibility, 100-achievement default and global statistics
https://partner.steamgames.com/doc/features/achievements - Valve Steamworks documentation, ISteamUserStats web API interface
https://partner.steamgames.com/doc/webapi/ISteamUserStats - VGC reporting on the September 2026 achievement leak across hundreds of upcoming games
https://www.videogameschronicle.com/news/huge-steam-leak-shows-achievement-lists-for-hundreds-of-upcoming-games-including-kingdom-hearts-4-and-persona-6/ - Gematsu reporting on the same leak
https://www.gematsu.com/2026/09/persona-6-kingdom-hearts-iv-and-other-steam-achievements-surface-in-large-scale-leak
