STS2 Couch Co-op (Split Screen)

Description
LocalCoop is an experimental same-machine local co-op launcher and transport bridge for Slay the Spire 2.

It starts multiple local Slay the Spire 2 clients, assigns controller slots, runs a loopback broker, and bridges the game’s native multiplayer traffic between those clients.

This is an Experimental Alpha tested against Slay the Spire 2 v0.103.3 on Windows x64. Expect rough edges. This release does not promise polished split-screen presentation, full gameplay stability, compatibility with future STS2 updates, or compatibility with arbitrary mod combinations, though things should still work.

You can view/edit/download the source code from my Github: https://github.com/Bahnerbd/STS2CouchCoop

Installation instructions
Extract the zip into your Slay the Spire 2 install folder so it lands here:
Slay the Spire 2\mods\LocalCoopConfirm this file exists:
Slay the Spire 2\mods\LocalCoop\LocalCoop.json
Open PowerShell in Slay the Spire 2\mods\LocalCoop and run:
.\Start-LocalCoopClients.ps1 -ClientCount 4 -ControllerDevices '0,1,2,3'
For fewer clients:
.\Start-LocalCoopClients.ps1 -ClientCount 2 -ControllerDevices '0,1'
.\Start-LocalCoopClients.ps1 -ClientCount 3 -ControllerDevices '0,1,2'Convenience batch files are included to launch for 2, 3, and 4 players.

You may need to arrange or resize one or more of the windows depending on your system. 

Main features
This mod adds a multi-client launcher for local multiplayer, which launches the selected number of clients, a communication broker and wires steam controllers to the clients. I threw this together with a good amount of vibe coding and have really only tested in my local environments with the four controllers I have. If you discover bugs or would like to make a PR, you can submit them here: https://github.com/Bahnerbd/STS2CouchCoop, though I will likely only continue support for as long as I'm playing STS2 or until MegaCrit adds native local co-op, whichever comes first. 

Requirements
Slay the Spire 2 (Windows x64)
One controller per client or mouse to control the clients

Shout outs
OpenAI Codex, without which I'd have had to learn Godot before making this. 

Known Limitations
- Experimental alpha; full gameplay stability is not guaranteed. I've completed a few runs without any issues, but QA is limited to me.
- Controller/mouse cross-play is not supported.
- One controller per client is supported.
- One mouse/keyboard controlling all clients is supported.
- Multiple simultaneous mice through MouseMux or similar tools are untested and unsupported, though should work.
- Future Slay the Spire 2 updates may break compatibility.

Troubleshooting
Packaged launches write configs and broker logs to:
%APPDATA%\SlayTheSpire2\LocalCoopIf PowerShell blocks the launcher, use:

powershell -ExecutionPolicy Bypass ...