Find yourself lost in the Backrooms in this co-op journey for 1 to 4 players. Explore eerie levels, solve puzzles, and find your way out using scavenged items. Entities lurk everywhere, and the deeper you go, the deadlier it gets.

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 26205320
Update posts
30 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 |
|---|---|---|
| 26205320 | Small Halloween Update! - Backrooms Lost Unit 0.0.4 | |
| 26011797 | None posted |
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 |
|---|---|
| 5 Oct 2026 | Hotfix 0.0.3V8 Patch notes |
| 23 Sept 2026 | Hotfix 0.0.3v7 Patch notes |
| 26 Aug 2026 | Hotfix 0.0.3v6.1 Patch notes |
| 26 Aug 2026 | Hotfix 0.0.3v6 Patch notes |
| 23 Aug 2026 | Hotfix 0.0.3 #5 Update |
| 11 Aug 2026 |
| App | Players now | Latest build |
|---|---|---|
| Backrooms Lost Unit Playtest · App 4288560 | 0 | 26410905 · |
Separate Steam apps for test, staging and playtest versions of Backrooms Lost Unit. 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
| Hotfix 0.0.3 #4 Patch notes |
| 7 Aug 2026 | Hotfix 0.0.3 #3 Patch notes |
| 17 Jul 2026 | Hotfix 0.0.3 #2 Patch notes |
| 9 Jul 2026 | Hotfix 0.0.3 #1 Patch notes |
| 27 Jun 2026 | Hotfix 0.0.2 #8 Patch notes |
| 25 Jun 2026 | Hotfix 0.0.2 #7 Patch notes |
| 22 Jun 2026 | Hotfix 0.0.2 #6 Patch notes |
| 17 Jun 2026 | Hotfix 0.0.2 #5 Patch notes |
| 11 Jun 2026 | Hotfix 0.0.2 #3 Patch notes |
| 10 Jun 2026 | The Hub Update Is Here! Update |
| 7 Jun 2026 | Hotfix 0.0.2 #2 Patch notes |
| 4 Jun 2026 | Hotfix 0.0.2 Patch notes |
| 2 Jun 2026 | Hotfix 0.0.1 #10 Patch notes |
| 31 May 2026 | Hotfix 0.0.1 #9 Patch notes |
| 30 May 2026 | Hotfix 0.0.1 #8 Patch notes |
| 28 May 2026 | Hotfix 0.0.1 #7 Patch notes |
| 26 May 2026 | Hotfix 0.0.1 #6 Patch notes |
| 26 May 2026 | Hotfix 0.0.1 #5 Patch notes |
| 25 May 2026 | Voice Chat Temporarily Disabled Patch notes |
| 24 May 2026 | Hotfix 0.0.1 #4 Patch notes |
| 23 May 2026 | Hotfix 0.0.1 #3 Patch notes |
| 23 May 2026 | Hotfix 0.0.1 #2 Patch notes |
| 21 May 2026 | Hotfix 0.0.1 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