Table of Contents

S1API

S1API is a modular, developer-friendly API for building mods for Schedule One. It provides a stable abstraction layer over the game's internals with a focus on:

  • Cross-compatibility between Mono and IL2CPP
  • A first-class Phone App framework
  • A lightweight UI factory for fast, consistent UI creation
  • An ergonomic save system for mod data
  • High-level wrappers for common systems (Phone Calls, Quests, NPCs, Items, etc.)
  • Clean logging utilities

The goals are predictable behavior, safe integration with the base game, and a smooth developer experience.

Highlights

  • Cross-runtime configurations: MonoMelon, Il2CppMelon
  • Phone App lifecycle: registration, icon spawning, open/close handling, input integration
  • UI primitives: panels, lists, buttons, layouts, and helpers via UIFactory
  • Saveables: annotate fields and get robust JSON persistence per-save-slot
  • Phone Calls: define callers, build multi-stage calls, and queue safely into the game's system

Example Projects

For practical, production-ready examples:

  • S1API NPC Examples - Complete custom NPC implementations covering customers, dealers, dialogue systems, schedules, and UI integration
  • S1NotesApp - Full in-game Notes application using S1API's PhoneApp and Saveables systems
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