This is a new and improved official version of the Nucleus Co-op application and is part of the SplitScreen.Me Github organization.
This new version is based off of the Nucleus Co-op Alpha 8 Mod build and features a ton of enhancements.

Note: Some Nucleus Co-op hook dlls and Goldberg emulator, used by Nucleus, can sometimes be detected as potential threats by Microsoft Defender and other anti-viruses or web browsers: this is 100% a false positive see here and here. You may have to allow Nucleus Co-op as an exception before extracting.

📚 Prerequisites

• .NET Framework 4.7.2 or higher: Microsoft direct download link.

• Microsoft Visual C++ 2015-2019 Redistributable (both x86 and x64): Microsoft direct download x86, Microsoft direct download x64.

• Microsoft Edge WebView2 (Only if the downloader gets stuck on loading screen): Microsoft Edge WebView2.

💻 Installation

• Installation Guide

• FAQ

• Download The Installer

• Download The Zip Archive (password : nucleus)

👥 Social

• Official website.
• Subscribe to the official Nucleus Co-op subreddit.
• Join the official Nucleus Co-op Discord server.
• Join the official Nucleus Co-op Patreon.

📝 Changelog for this release

• New native SDL2 support.
• New dependencies downloader (Microsoft Visual C++ 2015 - 2022 Redistributable, Microsoft WebView2 Runtime).
• Added game search and sorting functions.
• New multiple players per instance UI assignation support (Xinput/Proto Xinput, SDL2).
• Added per game "use api index" option in the game options menu, bypasses the general setting. There is a similar option for guest controllers only for handlers with multiple players per instance support.
• New Nucleus_Launcher.exe, a helper to check for .Net framework download and installation.
• The Nucleus Co-op window can now be resized/maximized/minimized without resetting the current setup.
• Fixed the backup function not working if a Nucleus player nickname is equal to the Windows user name.
• Modified backup function so it does not return an error if a file does not exist but skip it instead, better logging too.
• All Nucleus prompts and process pickers will now close automatically on session end, whether manually or due to an error.
• Fixed an UI bug where it was not possible to select the same game after ending a session in some cases.
• Fixed player being deleted if a controller is unplugged during very early handler setup in some cases.
• Added Messenils Direct Input co-oplevel unlocker (helps splitting mouse cursor in some games).
• Added a new hotkey listener to Nucleus.Gaming.dll, so hotkeys processing no longer relies on the Nucleus window (mainly for further development purposes).
• Added exFat format check for game path and Nucleus installation path.
• Added new option Game.DpiAwarenessMode as a successor to DPIHandling that is now deprecated. DpiAwarenessMode.HighDpiAware is now the default and should fix most instances scaling issues at display scales higher than 100%.
• Moved the "Unlock original game files" function so it executes earlier (some files were copied before its execution).
• Added a new "pass-through locked inputs state" flag to Game.CustomHotkeys.
• It's now possible to use a shorten link in all handler prompts (only one per prompt).
• It's now possible to use a shorten link in the handler notes (only one).
• Added per game Steam language option in game options menu.
• Fixed handlers using ForceBindIP not starting if there are special characters in the Windows username.
• Improved "Toggle Top Most" hotkey for better windows minimize/restore syncing (game windows, merger window, etc).
• Fixed DirectInput gamepads not being detected correctly after being turned off/on.
• Improved detection (connection/disconnection) for all gamepad apis. This fixes many UI inconsistencies and backend bugs.
• Game screenshots (backgrounds) can now be in .png, .jpeg, .jpg, .bmp, or .gif formats and can have random names, allowing you to simply drag and drop them into the Nucleus game screenshots directory.
• Game covers can now be in .png, .jpeg, .jpg, .bmp, or .gif formats but still need to be named using the Game.GUID value from the handler.
• More OneDrive checks.
• Added installation path in the error window and show if OneDrive is enabled.
• Added installation path and Nucleus Co-op version at the top of the debug log.
• Added Game.ExecutableNames = ["gameExe1.exe","gameExe2.exe","gameExe3.exe"] which allow to choose among many game executables to add a game to Nucleus. Game.ExecutableName should not be used with it.
• Can now highlight handler notes text in any rgb formatted color.
• Fixed Steamless patch not applying in some cases.
• Fixed a handler update bug where the current version was downloaded in place of the latest.
• New optional profile gamepad assignation method by button press, so gamepads can be assigned dynamically/manually when loading a profile, best to use with custom nicknames.
• More QOL improvements on the setup screen and many bug fixes.

Special thanks to imniko a.k.a solewalker for his contribution to the custom SDL2 dlls code.