PartyDeck is a split-screen game launcher for Linux / SteamOS

Now this is some seriously cool software and I love to see it. PartyDeck is a new tool that can help you run various games in local split-screen, even if they don't actually support it.

How? It runs multiple copies of the same game and sorts out all the connections for you, and will even automatically fit all the windows onto your screen. So it's not actual local split-screen, it's faking it but it's a fantastic idea to make gaming more accessible for people to play together.

As the developer explains how it works:

• KWin Session: This KWin Session displays all running game instances and runs a script to automatically resize and reposition each Gamescope window.
• Gamescope: Contains each instance of the game to its own window. Also has the neat side effect of receiving controller input even when the window is not currently active, meaning multiple Gamescope instances can all receive input simultaneously
• Bubblewrap: Uses bindings to mask out evdev input files from the instances, so each instance only receives input from one specific controller. Also uses directory binding to give each player their own save data and settings within the games.
• Runtime (Steam Runtime/Proton): If needed, the app can run native Linux games through a Steam Runtime (currently, 1.0 (scout) and 2.0 (soldier) are supported) for better compatibility. Windows games are launched through UMU Launcher
• Goldberg Steam Emu: On games that use the Steam API for multiplayer, Goldberg is used to allow the game instances to connect to each other, as well as other devices running on the same LAN.
• And finally, the game itself.

There are various limitations, and the developer is honest about it being the "first serious software project I've ever done" and so it may be a little on the messier side.

You can check it out on GitHub.