🚀 First Co-op Beta Playtest Releasing to Players
After months of testing and iteration, we’ve reached a version of the co-op mode that, while not perfect, is stable enough to be shared with players. This marks a huge milestone for the project — and your feedback and bug reports have played a critical role in getting us here. Thank you.
This release is available as a public_testing beta playtest, and we encourage all notified players interested in multiplayer to give it a try. It’s still a work-in-progress, but we believe it’s good enough to start real gameplay and stress testing.
We are already working on a hotfix update that addresses some of the most urgent known issues. We’re also preparing the next version of the update with more content and deeper systemic changes.
This build doesn’t include everything we originally planned — it’s a compromise between overall stability and the need to finally get co-op into your hands.
Over the last two years, 1,510 co-op–related tickets have passed through our tracker — covering bugs, suggestions, and task implementations. What you see in this devlog is only a small slice of what separates the last public version from this current co-op beta.
In parallel, we’ve also worked through a large number of general improvements unrelated to multiplayer — including crash handling, graphics quality, stability, performance and other foundational systems.
Many of those additional tasks are still in progress. Some of the things we’re building now won’t be visible until a month, two, or three from now.
Thank you for your trust, feedback, and ongoing support. Let’s keep pushing this mission forward — together.
The Occupy Mars Team
🔧 How to Join and Host Co-Op Sessions
To access the Co-op Beta, you need to switch your game branch to public_testing on Steam. Important: If you haven’t previously signed up for the beta or participated in pre-EarlyAccess playtests, the co-op mode will not be working for you unless you sign up for the Occupy Mars: Co-Op Playtest button.
How to activate the first co-op playtest:
Open Steam and go to your Library.
Make sure the product Occupy Mars: Co-Op Playtest is visible in your game library.
Right-click on the main game - Occupy Mars: The Game and select Properties.
In the left-hand menu, click the BETAS tab.
In the dropdown labeled “Select the beta you would like to opt into”, choose: public_testing - public testing version
Close the Properties window — Steam will automatically download the beta version.
Once updated, the game should display [public_testing] next to the title in Steam.
If you don't see the beta tab:
Make sure you're online in Steam.
Try restarting the Steam client.
If you launched the public_testing don't have the co-op buttons active in the game's main menu:
Wait for the next batch of playtest invites as we scale up and let more martians in.
🧭 Starting and Joining Co-op Games
After launching the game, go to Start Game → Multiplayer (or click Online CoOp (Beta)).
To host a game:
Click Create Game. While most settings are currently locked, you can:
Choose the starting location.
Select a save to continue from.
Copy the join code to share with other players.
To join a game:
Use Search Game in the Multiplayer menu, or:
Choose Join Game and paste the lobby code provided by the host.
If you're the host, you'll see a notification with the nickname of any player requesting to join.
⚠️ Current Limitations of Co-Op Beta
The following features are not yet available in this build:
Kicking or banning players
Vote-to-kick system
Password-protected lobbies
Text or voice chat (chat is enabled in lobby only)
Custom game names
Weather events
Rover and Mars Truck
Some buildings and technologies
Antennas, drop events and pendrives
Most of these features will be introduced in upcoming updates.
💾 Saving and Hosting Notes
The lobby creator is the host. Host acts as the server. If the host quits without saving — and no other player saved — progress will be lost.
Any player can create a save, and you can resume the game from any previously saved co-op session from any player (not only from the host).
👥 Inviting Friends via Steam
If you’re already in the game, you can invite your Steam friends through the overlay:
Press Shift + Tab to open the Steam overlay.
Open a chat with the friend you want to invite.
Click the arrow near the message field and choose Invite to Game.
Alternatively, paste the session code directly into the chat.
This method works only if you’re hosting or already in a multiplayer lobby.
🛠️ Troubleshooting Multiplayer Issues
If you're experiencing crashes, desync, save/load issues, or connection problems, please follow these steps:
Send log files to: [email protected]
Logs are located at: C:\\Users\\%USERNAME%\\AppData\\LocalLow\\PyramidGames\\OccupyMars\\Player.log
Logs are overwritten with each game launch. Send them immediately after the issue, before restarting. If you forgot once, there's a copy of previous log in Player-prev.log file.
The game stores logs from the current and previous session.
Please identify which log is from the host (contains the most data) and which from the clients.
If the issue is tied to a save, attach it:
Save location: C:\\Users\\%USERNAME%\\AppData\\LocalLow\\PyramidGames\\OccupyMars\\SaveData
Zip the entire folder of the affected save and send it to the email above, along with a short description.
Describe the issue clearly:
What happened? When?
What were the host and each player doing at the time?
Can the issue be reproduced?
Where to report:
Steam Community Co-Op Playtest Bugs & Issues
Discord Mars Coop Discussions
Email (recommended for anything that requires attachments) [email protected]
✨ New Features & Improvements in v0.226
General Content
Added dirty variants for Outpost decorations to enhance realism.
Added dust accumulation on loot found in Outposts.
Improved build bounds handling for interior structures.
Improved visual quality of weather effects.
Improved general responsiveness of in-game interactions.
Prepared additional models for interior and exterior decorations.
Co-op Specific Features & Improvements
Added multiplayer online Co-op game mode
Implemented player inventory synchronization for improved stability.
Added new ID system to ensure consistent player handling in co-op sessions.
Introduced Playfab Party integration for a more reliable multiplayer backend.
Enabled connection status messages for players joining co-op sessions.
Added synchronization for oxygen usage from buildings, backpacks, and life support systems.
Enabled synchronization of bottle filling from control panels.
Integrated synchronization systems for the battery rack and heavy suit.
Implemented co-op support for centrifuge mechanics.
Deployed shared loot mechanics for co-op players.
Rolled out global loot spawning system for Outposts.
Introduced synchronization for cable animations.
Integrated unlock conditions for decorations and tech tree elements in co-op.
Introduced co-op version of the technology tree.
Enabled automatic decoration unlocks at co-op game start.
Developed enhanced authority management system for co-op sessions.
Added essential co-op information panel/pop-up for players.
Implemented new, more friendly UI for co-op and other game modes in the main menu.
Implemented handling for various network disconnection scenarios (e.g., cable unplug, router restart).
Added support for keyboard and gamepad navigation in the co-op lobby.
Introduced synchronization of avatars for non-friend players (WIP).
Applied refined design updates to sleeping panels.
🛠️ Fixes & Changes
🛠️ High Priority Fixes
Fixed problem with disappearing tracker’s colours.
Fixed issue where dust devils could affect the player even when inside a warehouse.
Fixed bug where assembling Rocket A Kit caused the player’s hand to become bugged.
Fixed miner allowing to unload resources into a container that was already full.
Fixed several crashes cases that occurred during game launch.
🔧 Normal Priority Fixes
Optimized LODs and fixed missing materials in cracks.
Fixed issue with clothing items duplicating unexpectedly.
Fixed issue with double rock spawning caused by terrain generation system.
Fixed weather effects being visible while the player was inside.
Fixed issue with night vision not turning off properly.
Fixed missing home button on the tablet interface.
Fixed incorrect estimation of sleep duration.
Fixed edge case where player had access to night vision despite not unlocking it.
Fixed missing rock drilling particles from other players.
Fixed issue where some rocks lacked physics.
Removed small levitating object from the environment.
Fixed inventory box requiring double ESC press to close.
🧹 Low Priority Fixes
Fixed incorrect slot numbering for workshop structures.
Fixed missing black backpack in player customization.
Improved visibility of PCB parts on zoom screen.
🐞 Known Bugs
⚠️ Major Issues
Resource amount desynchronization (water, oxygen, electricity) may sometimes occur when players use tanks or batteries separately — especially when refilling suits manually from sockets. (We have a fix ready, but it affects core systems and requires extended testing.)
Players may still experience issues with joining, rejoining, being disconnected, kicked to lobby, or game crashing — both during game launch and active sessions.
Plant state issues during replanting — either by hand or using crates — especially when stacking previously separate plants. (Hotfix is ready and will be included in the first minipatch.)
Items may occasionally disappear from inventory boxes, refrigerators, or storages. (Likely fixed — patch coming in the first minipatch.)
In single-player mode, centrifuge only works while the player is actively looking at its panel. (Hotfix already prepared — included in the first minipatch.)
Some clients may load into the skybox or spawn far from the base after reconnect.
Rare cases of invisible or partially loaded player models.
🛠️ Other Known Issues
Temperature, oxygen level, or UI indicators may desynchronize between players.
Differences in plant states between host and clients (e.g., wilted vs. healthy).
Character appearance may differ from selected setup (e.g., wrong hairstyle or color).
Deathboxes may appear under terrain or in unreachable locations.
Grinder or tool interactions may trigger "null" errors on certain objects.
Rejoining players may spawn hundreds of meters from the intended respawn point.
Shared use of fridges, printers, or panels can lead to UI glitches or lag.
Vehicle controls or camera may behave erratically in some situations.
In rare cases, players fall under the terrain, lose movement, or get stuck.
Lobby host may occasionally switch unexpectedly. (Rare)*
💬 We're Listening
We hope you enjoy playing together on Mars. As always, we’re monitoring feedback actively on both Steam Community and our Discord server — don’t hesitate to reach out if you run into issues or want to share your thoughts.
Happy testing, Colonists!