AgenticSTS-Mod

AgenticSTS-Mod

A Slay the Spire 2 game mod that exposes the live game state and player actions over a local HTTP API, so an external agent can observe and play the game. It is the bridge used by the AgenticSTS research agent.

Credit & provenance

This mod is a fork of CharTyr/STS2-Agent, created and originally authored by CharTyr. All credit for the original mod design and implementation goes to CharTyr.

This directory contains only the C# game mod (STS2AIAgent/). The upstream project also ships an MCP server and assorted tooling; those are not included here because the AgenticSTS agent talks to the mod's HTTP API directly with its own client. See VENDOR.md for the full fork history and the exact upstream merge-base.

License

GNU Affero General Public License v3.0 (AGPL-3.0). See LICENSE. This license is inherited from the upstream project and governs this entire directory. If you distribute or run a modified version of this mod, the AGPL-3.0 terms apply. (Note: the AGPL applies to this mod only — the rest of the surrounding repository is licensed separately.)

Technical overview

• Stack: .NET 9 / Godot 4.5 / Harmony.
• API: HTTP REST on localhost:8128 (configurable):
  • GET /state — current game state
  • POST /action — submit a player action
  • GET /events/stream — server-sent event notifications
• Custom files (relative to upstream): Game/GameActionService.cs, Game/GameStateService.cs.

Build

cd STS2AIAgent
dotnet build -c Release

Building requires the STS2 game DLLs. They are read from the default Steam install path:

C:/Program Files (x86)/Steam/steamapps/common/Slay the Spire 2/data_sts2_windows_x86_64/

Override the location by setting the STS2_DATA_DIR environment variable before building. See STS2AIAgent/local.props.example for the project's local build properties.

Deploy

Copy the built mod into the game's mods/ directory and launch the game:

STS2AIAgent.dll
STS2AIAgent.pck
mod_id.json

The built .dll/.pck land in STS2AIAgent/bin/Release/net9.0/. A pre-built copy is also tracked at build/mods/STS2AIAgent/ for clone-and-deploy without setting up the .NET SDK.

Disclaimer

Not affiliated with, endorsed by, or sponsored by Mega Crit (developer of Slay the Spire 2).