How it works
From the developers' pinned Launch FAQ:
"GRAIN ROT uses player-hosted Steam lobbies. Players join through Steam invites or their Steam friends list."
So there is no account system and no server list of your own — it runs on Steam's lobby plumbing. One player hosts; everyone else joins that person's session.
Everyone needs their own copy of the game, also developer-stated. See price.
Three ways in
| Route | How | Since |
|---|---|---|
| Steam invite | Invite directly from the Steam overlay or friends list | Launch |
| Friends list | Join a friend's session from your Steam friends list | Launch |
| Public browser | Browse and join public servers in game | Patch 1.07 |
The FAQ was written before the browser shipped — it says "We are working on public lobbies, and a lobby browser". Patch 1.07 (12 August 2026) delivered it, along with password-protected servers.
Privacy modes, and the change that matters
Patch 1.04 added lobby privacy and max player count settings under the multiplayer options tab, plus a view-lobby menu with per-player mic volume, kick and ban.
Then patch 1.07 changed how friends-only actually behaves:
"The friends only and invite only privacy mode now allows for friends of anyone in the server to join, not just the host."
⚠️ This is the fix for the classic co-op problem. Before 1.07, a friends-only lobby was gated on the host's friends list — so a group of four where two people did not know the host could not assemble. Now anyone already in the server can pull in their own friends.
If you cannot join a friend
Check the patch you are on first. Patch 1.05 (10 August 2026) lists:
"Fixed a bug where you could not join friends when lobby privacy was set to friends."
If that is what you are hitting on a current build, it is worth reporting rather than working around — see troubleshooting.
Patch 1.04 also fixed a related annoyance: items owned by a client are no longer destroyed when they leave. They drop on the ground or go to the lost-and-found crate instead.
How many people should you bring
Four. Not because it is a cap — there isn't one — but because the developers say the game is "currently balanced and best played with around four players in online co-op."
The full answer, including what happens above four, is on how many players.
Playing with strangers
Public lobbies exist as of 1.07, and so does the obvious concern about them. There is an active community request for a permission system so that guests who joined through an open lobby cannot immediately interact with your Outpost furniture, shop and elevator.
⚠️ That is a suggestion, not a feature. Nothing like it exists today, and no developer response is attached. If you host publicly, the host tools you actually have are password protection, kick and ban.
What is not confirmed
- Whether there is any anti-griefing protection for hosts beyond kick and ban
- What the max player count setting tops out at
- Whether progress is shared or per-player when you join someone else's session — no source describes what a guest keeps
- Whether the developers plan to act on the permission-system request