Nucleus Co-Op FAQ
Answers to the most frequently asked questions about Nucleus Co-Op — covering safety, legality, game compatibility, controllers, save files, and more.
General
What is Nucleus Co-Op? +
Nucleus Co-Op is a free, open-source Windows tool that adds split-screen to PC games that do not support it out of the box. It runs multiple copies of the same game on one PC, connects them for co-op play, and arranges the windows so each player has their own view.
Is Nucleus Co-Op safe to use? +
Yes. Nucleus Co-Op is safe when downloaded from the official GitHub page. Some antivirus tools, including Microsoft Defender, may flag support files as false positives. Add your Nucleus folder to Defender exclusions before extracting.
Is Nucleus Co-Op legal? +
Yes. You must own a legitimate copy of each game. Nucleus does not bypass copy protection or distribute game files — it only runs games you already own on one PC.
Is Nucleus Co-Op free? +
Yes, Nucleus Co-Op is completely free and open source on GitHub. Optional Patreon donations help support development.
Does Nucleus Co-Op work with pirated games? +
Game setups are built and tested for legitimate Steam copies. Unofficial copies may be missing files or Steam features, so compatibility is not guaranteed.
Compatibility
How many games does Nucleus Co-Op support? +
As of 2025, Nucleus supports over 800 games through community game setups on the SplitScreen.Me library. New games are added regularly.
Does Nucleus Co-Op work on Steam Deck? +
Nucleus is a Windows app and does not run natively on SteamOS. Some players use Windows on Steam Deck, but Linux/SteamOS mode is not officially supported.
Does Nucleus Co-Op work on Mac or Linux? +
No. Nucleus requires Windows 7 or newer. There is no official Mac or Linux version.
Does Nucleus Co-Op work with Epic Games or Game Pass? +
Some Epic versions work if the game setup notes mention Epic support. Xbox Game Pass titles are often blocked by DRM. Check the setup notes for your game.
Does Nucleus Co-Op work offline? +
Yes. After you download game setups, Nucleus works offline. Most games connect instances on your local network without internet.
Controllers & Input
What controllers does Nucleus Co-Op support? +
Most games work best with Xbox-style controllers (Xbox 360, One, Series). PlayStation controllers need DS4Windows. Some games also support multiple keyboards and mice.
My PS4 or PS5 controller is not being detected. What should I do? +
Run DS4Windows before opening Nucleus so your PlayStation controller appears as an Xbox-style device. If you get double input, use HidHide to hide the native device.
My controller controls both screens at once. How do I fix it? +
Usually the game sees both native and emulated input. Use HidHide to hide the native controller and disable Steam Input if Steam is running.
What is the End key used for? +
Press End to lock or unlock input when a game supports multiple keyboards and mice. Lock input after instances are running so each device only controls its assigned window.
Technical
Where should I install Nucleus Co-Op? +
Use C:\NucleusCo-op. Do not install inside Program Files, inside a game folder, or in a OneDrive-synced folder. Some games need Nucleus on the same drive as the game.
Nucleus shows a OneDrive error. How do I fix it? +
Sign out of OneDrive and reset your Documents folder to C:\Users\YourName\Documents in folder Properties > Location.
Where are save files stored? +
Some setups save to C:\Users\YourUser\NucleusCoop. In Nucleus, select the game, open Game Options, then Open UserProfile Save/Config Path to find the folder.
Can I use Nucleus on two different PCs? +
Yes. Run Nucleus on each PC and connect over LAN. If the game uses Steam-style networking, assign different Steam IDs per PC to avoid conflicts.
Does Nucleus Co-Op Work With...
Does Nucleus Co-Op work with Steam? +
Yes. Steam is the primary supported platform. Most handlers are developed and tested using Steam versions of games. Make sure Steam is open before launching Nucleus if the handler requires it. Some handlers require Steam to be running for the Steamworks API.
Does Nucleus Co-Op work with Epic Games Store games? +
Some games work with EGS versions if the handler specifically supports it. Always check the game setup notes for your game. EGS support is more limited than Steam because fewer handlers have been tested with Epic game builds.
Does Nucleus Co-Op work with mods? +
It depends on the game and handler. The Elden Ring handler requires the Seamless Co-op mod. The Terraria handler works with tModLoader. Most handlers work with cosmetic mods but gameplay-altering mods that change network code may break LAN emulation.
Does Nucleus Co-Op save progress separately for each player? +
Many handlers create separate save folders for each instance, stored at C:\Users\YourName\NucleusCoop. To find the exact save path, select your game in Nucleus and click Game Options > Open UserProfile Save/Config Path. Some handlers share save data between instances.
Does Nucleus Co-Op work with pirated games? +
Handlers are tested on legitimate Steam copies. Pirated games often lack Steamworks DLLs that handlers depend on, have modified executables that break hooks, or require DRM bypasses that conflict with Nucleus. Pirated game support is not provided by the community.
Does Nucleus Co-Op support PS4 and PS5 controllers? +
Yes, via DS4Windows. DS4Windows converts PS4 (DualShock 4) and PS5 (DualSense) controllers into XInput devices that Nucleus can detect. Run DS4Windows before opening Nucleus. Use HidHide to prevent double-input from the native DirectInput signal.
Does Nucleus Co-Op work on Windows 11? +
Yes. Nucleus Co-Op is fully compatible with Windows 11. You may also need to install DirectX End-User Runtime. Ensure your display scale is 100% and Defender exclusions are set correctly.
Does Nucleus Co-Op work on cracked games? +
This is not officially supported. Cracked executables behave differently from legitimate ones, and hook injections may fail. The Nucleus community does not provide support for cracked game issues.