FsmMaster for Hollow Knight and Silksong

A live PlayMaker FSM inspector and editor for Hollow Knight and Hollow Knight: Silksong. View any FSM in the game as an interactive graph, edit its states, variables, and transitions while the game runs, and save your edits to reapply them later.

Press F3 to toggle the overlay. You can bind a key for a monitor only mode. Both are rebindable in-game via BepInEx's Configuration Manager (Silksong) or the Modding API's own mod settings menu (Hollow Knight 1.3.1.5/1.4.3.2/1.5.78); on Hollow Knight 1.2.2.1, whose Modding API predates in-game settings menus, rebind by editing the mod's saved settings file directly.

Source code and latest release available at FsmMaster Github Repository

For any questions or bug reports, please join the Modding Discord or Speedrunning Discord.

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• FsmMaster for Hollow Knight and Silksong
  • Features
  • Coming Soon
  • Controls
    • Panel Controls
    • Graph Controls
    • State Panel
    • Sequencer
  • Installation
  • Credits

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Features

• Graphic, customizable UI with performance toggles for lower-end machines.
• FSM editing and viewing with live information - watch states, variables, and transitions update in real time as the FSM actually runs.
• Rebindable hotkeys (see above for how, per platform).
• Savestate support with DebugMod - active FSM edits are saved into and restored from savestates automatically.
• Custom RNG sequencing - replace an FSM's random event picks with a fixed, ordered sequence you control.
• Hidden variable editing, including variables PlayMaker doesn't normally expose in its own editor.
• Monitoring panel compatible with multiple simultaneous FSMs.
• Interactable graph - click and drag your way through an FSM's states, transitions, and events instead of reading raw data.
• Custom config saving/loading, with optional auto-load on scene change.

Coming Soon

• Adaptive RNG, to make practicing attacks faster based on what you're struggling with
• Timer Mod integration, starting and stopping the timer based on Fsm values
• Sequencers for more actions

Controls

Panel Controls

• Open - choose an FSM to display.
• Save - save edits to file.
• Load - load edits from file.
• Undo - undo last edit.
• Reset - reset FSM to default.
• Hide - hide graph.
• Auto - load last saved file automatically upon scene change.

Graph Controls

• Scroll Wheel - zoom.
• Drag - pan.
• Click - select a state, event, or transition.
• Double Click - change states.
• Right Click - disable a state or transition.
• Click and Drag from a transition - retarget it to a different state.

State Panel

• Edit most basic variable types directly.
• Click the blue dot next to a variable to add it to the monitor panel.

Sequencer

• Drag events to build a custom sequence, and rearrange them to replace an FSM's random event selection with a fixed pattern.

Installation

Game	Manager	Manual download	Install to
Silksong	Thunderstore / Cogfly	FsmMaster-silksong.zip	BepInEx/plugins/
Hollow Knight 1.5.78	Lumafly / Scarab	FsmMaster-hk1578.zip	hollow_knight_Data/Managed/Mods/
Hollow Knight 1.4.3.2	— (manual only)	FsmMaster-hk1432.zip	hollow_knight_Data/Managed/Mods/
Hollow Knight 1.3.1.5	— (manual only)	FsmMaster-hk1315.zip	hollow_knight_Data/Managed/Mods/
Hollow Knight 1.2.2.1	— (manual only)	FsmMaster-hk1221.zip	hollow_knight_Data/Managed/Mods/

[!IMPORTANT] For moderation reasons, the Silksong version requires Silksong.ModList to be installed. This mod is included in the Silksong release download. If Silksong.ModList is not installed, FsmMaster will silently fail to load.

[!TIP] FsmMaster works standalone, but installing DebugMod (Silksong) or DebugMod (Hollow Knight) alongside it gives you savestate support - active FSM edits are automatically captured and restored when you save or load a savestate. I recommend installing DebugMod for the best experience.

Credits

• Core development - ConstructiveCynicism
• FSM edit helpers derived from Silksong.FsmUtil - silksong-modding (EUPL-1.2)
• Graph layout and FSM visualization conventions inspired by FSMExpress - nesrak1
• Built on DebugMod's savestate system - Silksong.DebugMod / HollowKnight.DebugMod

License

FsmMaster Copyright (c) 2026 ConstructiveCynicism Licensed under the EUPL-1.2.

This product includes code derived from Silksong.FsmUtil Copyright (c) silksong-modding Licensed under the EUPL-1.2 - https://github.com/silksong-modding/Silksong.FsmUtil The derived code has been modified by ConstructiveCynicism since 2026-07-20.

Graph layout and FSM visualization conventions inspired by FSMExpress (nesrak1). Built on Silksong.DebugMod's savestate system.