The Boxer

The Boxer is an unofficial custom character mod for Slay the Spire 2. It adds a complete boxing-themed card pool built around reading opponents, creating openings, maintaining pressure, dodging attacks, and answering with counters.

View The Boxer on the Steam Workshop

Current release: v0.2.0, built and tested for the main Steam version of Slay the Spire 2, v0.107.1, with BaseLib v3.3.2. See the changelog and v0.2.0 release notes.

Features

• A fully playable custom character with custom combat, selection, shop, rest-site, and death artwork.
• 89 playable cards, including a complete basic, common, uncommon, and rare card pool.
• Five interconnected mechanics: Counter, Pressure, Opening, Dodge, and Heavy attacks.
• A starter relic, its Ancient-upgraded form, and additional custom relics.
• Six custom events, including character-specific content and a training-dummy encounter.
• English localization, card art, status icons, relic art, and custom character presentation.

Requirements

• A legitimate installation of the main Steam version of Slay the Spire 2 v0.107.1. This is the release target and minimum version declared in BoxerMod.json.
• BaseLib version 3.3.2 or newer.

The game and its modding API are still evolving. A game or BaseLib update can temporarily break the mod even when the declared minimum versions are satisfied. Please report reproducible problems with the game version, BaseLib version, and relevant logs.

Installation

Steam Workshop

1. Install and enable BaseLib.
2. Subscribe to The Boxer.
3. Let Steam download the item, then start the game with mods enabled.

Manual installation

1. Install BaseLib 3.3.2 or newer.
2. Download a packaged release of The Boxer.
3. Create a BoxerMod folder inside the game's mods directory.
4. Place BoxerMod.dll, BoxerMod.json, and BoxerMod.pck directly inside that folder. A matching .pdb is optional and is only useful for diagnostics.
5. Start the game with BaseLib and The Boxer enabled.

On a default Windows Steam installation, the destination is:

C:\Program Files (x86)\Steam\steamapps\common\Slay the Spire 2\mods\BoxerMod\

If Steam is installed elsewhere, use that library's Slay the Spire 2/mods/BoxerMod directory instead.

Building from source

Prerequisites

• .NET 9 SDK
• Slay the Spire 2 installed locally
• MegaDot 4.5.1 Mono, matching the engine version expected by the game

The project normally discovers a standard Steam installation automatically. For a non-standard installation, pass Sts2Path to MSBuild. Pass GodotPath as the full path to the MegaDot executable when publishing.

From the repository root:

Copy-Item .\local.props.example .\local.props
# Edit local.props and set GodotPath. Set Sts2Path there only if auto-discovery fails.

dotnet restore .\BoxerMod.csproj --locked-mode
dotnet publish .\BoxerMod.csproj --no-restore -c ExportRelease

Alternatively, Sts2Path and GodotPath can be supplied directly as MSBuild properties instead of using local.props. The build targets copy the manifest and managed assembly into mods/BoxerMod; publishing also exports the PCK. A distributable installation consists of the resulting .dll, .json, and .pck files.

Do not build the PCK with a newer Godot/MegaDot release unless the game has moved to that engine version; incompatible resource formats may prevent the game from loading it.

Repository and dependency status

This repository contains the source and development assets for the mod. Generated Godot caches, IDE state, local tool paths, SteamCMD files, Workshop staging content, and build output are intentionally excluded from version control.

BaseLib and the Slay the Spire 2 assemblies are external dependencies and are not bundled in this repository. Their licenses and terms remain with their respective authors. The NuGet dependency versions used for development are pinned in BoxerMod.csproj; the runtime minimum for BaseLib is declared separately in BoxerMod.json.

Credits

The Boxer was created by RiddlerQ.

This is an unofficial fan-made mod. It is not affiliated with, endorsed by, or sponsored by Mega Crit. Slay the Spire and Slay the Spire 2, along with their names, characters, and related intellectual property, belong to Mega Crit and their respective rights holders.

License

The source code is available under the MIT License. Artwork and all other non-code assets are All Rights Reserved. See LICENSE.md for the exact terms.