15th Prison is a horror escape game. There is no exit from this prison. But examine your surroundings carefully and do not ignore any abnormalities. Take the envelope in each block and move on. Your carelessness may result in death.

Public builds
—No reading yet
Counted once we have watched for 90 days (since 21 Oct 2026)
Distinct builds deployed to a game's public (default) Steam branch, as Steam's client network describes them.
Checked within minutes of each Steam change. Observed since 21 Oct 2026.
Source: Steam client network (PICS), App info, public branch. Full methodology
Latest public build
Build 18701366
Update posts
0 postsPosts announcing an update, tagged or not
Posts in a game's official Steam news feed that announce an update: tagged as patch notes by the developer, or plainly about a patch or a released update.
Source: Steam Web API, ISteamNews/GetNewsForApp. Full methodology
Typical gap between builds
Not enough builds yet| Build | Went live | Patch notes |
|---|---|---|
| 18701366 | 2 June Update |
From Steam’s client network, last checked . Builds before 21 Oct 2026, when we started watching, aren't listed. Patch notes are the developer’s update post from an hour before to a day after the build. Not every build gets one. How we count
| Posted | Update |
|---|---|
| 2 Jun 2025 | 2 June Update Patch notes |
| 23 May 2025 | 23 May Update Patch notes |
| 21 May 2025 | 21 May Update Patch notes |
Steam keeps no record of past build numbers, so before 21 Oct 2026 a game’s update history comes from its own Steam news: posts tagged as patch notes, and untagged posts that plainly announce a patch or a released update. Older posts are still being read in, most played games first. How we count
| App | Players now | Latest build |
|---|---|---|
| 15th Prison Playtest · App 3682590 | Not yet | 18502985 · |
Separate Steam apps for test, staging and playtest versions of 15th Prison. They have no store page, so they aren’t counted as games or releases. Builds come from Steam’s client network, players from the Steam Web API every few hours. Steam gives no count for an app nobody can launch. How we count