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 comple