Moon Sweepers supports up to 16 players in an online co-op crew, and you can also play alone. The host picks a save slot and decides who may join; friends either find the crew by name in Join game or accept a Steam invite. Money and, since patch 1.0.3, upgrades are shared; tools and vehicles are not.
How to host a game
From the main menu choose Start game, pick one of the five save slots and set who can join before pressing Play. The three options are Friends only, Invite only and Public. With Friends only, your Steam friends can join without an invitation.
How to join a friend
Open Join game from the main menu: it lists open crews by the host's name with the number of players out of 16, and a Refresh button. Pick your friend's crew there, or accept their Steam invite. If an invite does not show in the game, open the Steam overlay's friends and chat window and join from there.
How to invite someone already in game
Press ESC, open Your crew and choose Invite friends; it sends a Steam invitation. The same screen lists everyone in the crew.
What the crew shares
- Money: one team wallet; purchases show what they leave in team funds.
- Upgrades: since 1.0.3 everyone uses the host's upgrade matrix, and one player's purchase upgrades the whole crew. Saves from before the patch keep the highest level anyone had bought.
- Cleaned ground: since 1.0.4 everyone sees the same cleaned ground, including robot trails, and dust no longer reappears.
- Belts: since 1.0.4 any crewmate can place splitters and mergers on belts built by others.
What stays personal
Each player buys their own vehicles in the Garage, and vehicle upgrades are personal too. The tools in your hand are yours, although upgrades bought for tools apply to everyone. Agree who buys what before spending, so two people do not pay for the same vehicle-side upgrade.
Host controls
The host can kick or ban anyone from ESC, Your crew. A banned player cannot rejoin that save until the host unbans them on the same screen.
Versions must match
Every crewmate has to run the same game version: 1.0.3 required all players on 1.0.3, and saves made in 1.0.4 cannot be opened by older versions. If a friend cannot join, check that both of you have updated.
Playing solo
Single-player is supported. The store lists it next to online co-op, and the game runs on Windows through Steam only, so there is no cross-play with consoles. Whether it runs without an internet connection has not been documented.
Can a crew keep playing without the host?
No. A Moon Sweepers world lives in one of the host's five save slots, and the store lists no dedicated servers, so the crew plays only while the host is in the game. Friends rejoin through Join game or a Steam invite once the host loads that slot again. Every player must be on the same version for the session to open.
Can you play Moon Sweepers offline?
Not as far as anyone has documented. The store lists a broadband internet connection in the minimum requirements, and the game checks that it was started through Steam: players who see "Moon Sweepers needs Steam" cannot get in until Steam recognises them. Solo play works, but plan on Steam being online; there is no official offline mode.