Backrooms: Lost Dimension is a single-player horror game with puzzles, survival, and an original story. Explore mysterious levels, journey through unknown dimensions, and uncover hidden secrets along the way. Play the first chapter for free and continue the adventure by unlocking the next ones.

Public builds
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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 23829396
Update posts
7 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 |
|---|---|---|
| 23829396 | Patch Notes - 20 June 2026 |
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 |
|---|---|
| 19 Jun 2026 | Patch Notes - 20 June 2026 Patch notes |
| 19 Jun 2026 | Hotfix: 19 July 2026 Patch notes |
| 18 Jun 2026 | Patch Notes - June 18, 2026 (Your criticisms have been heard) Patch notes |
| 18 Jun 2026 | Patch Notes — June 18, 2026 Patch notes |
| 17 Jun 2026 | Patch Notes 0.2.2 - 17/06/2026 Patch notes |
| 17 Jun 2026 |
| Update Notes – June 17, 2026 Patch notes |
| 11 Feb 2026 | PATCH NOTES #1 - BACKROOMS LOST DIMENSION DEMO 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