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UE5 PluginDecoupled C++ ArchitectureBlueprint Friendly

OSSIM

OSSIM is a desktop-environment simulation plugin for Unreal Engine 5. OSSIM provides a complete, persistent OS experience with a decoupled controller-view architecture, interface-driven UI, and a suite of 15 built-in apps.

Why Choose OSSIM?

OSSIM isn't just a UI kit — it's a plugin for a complete OS simulation. It handles the "boring" parts of OS simulation — window management, process tracking, and filesystem persistence — so you can focus on building your gameplay and apps.

The OS is auto-activated: In the OSSIM_DemoMap Outliner, locate BP_ScreenOS. Inside this actor, you'll find WBP_OS_Root (inherited from UOSOrchestratorWidget). The OS automatically initializes as soon as the widget is constructed during BeginPlay.

Press the F key to toggle the view to the PC screen or enter AFK mode. You can review this behavior in the OSSIM_DemoMap Level Blueprint.

Core Strengths

Decoupled Architecture

Uses a Controller (C++) and View (UMG) pattern. Logic is strictly separated from presentation.

Blueprint Friendly

Create new OS applications entirely in Blueprints using the BlueprintApp base class.

Interface-Driven UI

Widgets implement IAppContentWidget for automatic, type-safe initialization by the OS.

Virtual Filesystem

Linux-like VFS with per-user persistence for file and directory operations.

Software Center

Built-in app store with install/uninstall system, progress simulation, and per-user app registry.

Staged Session Flow

Includes Boot, Onboarding, Login, and Desktop stages out of the box.

Included Applications (15)

OSSIM comes with a suite of functional apps that serve as both tools and code references:

System & Tools

  • File Explorer: Navigate the VFS, manage files, context menus, and launch associated apps.
  • Task Manager: Visual monitor of running apps, processes, and synthetic CPU/memory metrics.
  • Settings: Profile, appearance (wallpaper), sound, and system information.
  • Software Center: App store for browsing, installing, and uninstalling applications.
  • Calculator & Calendar: Essential desktop utilities.

Productivity & Editors

  • Notepad: Multi-tab text editor with undo/redo, word-wrap, and zoom.
  • Code Editor: Syntax-highlighted editor with multi-language support (C++, JS, TS, Python), code folding, and file tree.
  • Terminal: Command-line interface with 27 commands across 18 handlers.
  • Mail: Full email client with compose, reply, forward, folders, search, and VFS JSON persistence.

Media & Entertainment

  • Media Viewer: Integrated support for viewing images and playing videos.
  • Music Player: Audio playback with playlists, shuffle, repeat, and volume control.
  • Browser: Embedded web browser powered by SWebBrowser.
  • Minesweeper: Classic game with 9×9 board, first-click safety, and timer.

No-Code Apps

  • Blueprint App: Create new applications entirely in Blueprints — no C++ required.

Documentation Guide

  1. Getting Started: Install the plugin and verify the core shell flow.
  2. Architecture: Deep dive into the controller-view pattern, core subsystems, and Slate widget integration.
  3. Window System: Window chrome, tabbed hosting, animations, and Z-order management.
  4. Extending OSSIM: Build your own apps using Blueprints or C++.
  5. Save And Session: User persistence, filesystem snapshots, and the install registry.
  6. Notification System: Toast notifications, severity levels, and auto-dismiss.
  7. Context Menu: Right-click context menus and custom actions.
  8. Apps Reference: Detailed documentation for each built-in application.
  9. API Reference: Quick-reference for all subsystem APIs and key structs.
  10. Changelog: Version history.

OSSIM is built for developers who spend countless hours creating computer systems. It brings a fully interactive operating system directly into Unreal Engine projects, enabling everything from hacking mechanics to complete in-game desktop experiences.