Backrooms Mainframe is a 1-6 player co-op horror game. Explore the labyrinthes while avoiding entities and other dangers while finding your way through.

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 16914597
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 |
|---|---|---|
| 16914597 | 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 |
|---|---|
| 28 Jul 2023 | HotFix 1 Patch notes |
| 28 Feb 2023 | Hotfix Patch notes |
| 23 Jan 2023 | Level 0 and balancing Patch notes |
| 22 Jan 2023 | HotFix#1 Patch notes |
| 11 Jan 2023 | Major Update Update |
| 4 Jan 2023 |
| Player name bug 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