Hey everyone,
I’m Michael from AfterPrime Systems. I’m sharing a free plugin that I built as part of a larger multiplayer gameplay suite.
AP Event Bus is a replicated pub/sub event system. One component on your GameState. Any actor publishes events by Gameplay Tag. Any actor listens by Gameplay Tag. Publishers and listeners never reference each other — fully decoupled.
I released this for free because I think every multiplayer project needs some version of this, and most people end up building one from scratch every time. If you find it useful, it’ll give you a sense of the architecture and quality standard across the rest of the AfterPrime suite.
WHY USE THIS INSTEAD OF ROLLING YOUR OWN
- Client-to-server routing is automatic — one PublishEvent node works from any machine. No authority checks, no separate client/server functions.
- Four delivery scopes: All (NetMulticast), OwnerOnly (Client RPC), ServerOnly, LocalOnly.
- Late-join cache — register tags as persistent and late-joining clients automatically receive cached event state. Match phase changes, captured objectives, world state all sync correctly for players joining mid-game.
- Two-tier delegate system — OnEventReceived (catch-all) and OnListenedEventReceived (filtered by tag). Use both simultaneously.
- Blueprint helper library — GetEventBusFromGameState, PublishEventOnBus, MakeEventPayload. Convenience functions available in any Blueprint graph.
WHAT’S INCLUDED
- C++ plugin with full source (Runtime module)
- Blueprint helper library with 4 convenience functions
- C++ demo character with input-driven examples across all four delivery scopes
- Quick Start Guide + full API Reference + Changelog
TECHNICAL DETAILS
- UE 5.4 – 5.7 supported
- Zero external dependencies, no GAS
- Server-authoritative, RPC-based replication (no replicated UPROPERTYs)
- Single component on GameState
LINKS
Fab (FREE): AP Event Bus - Replicated Event Messaging System | Fab
Discord: AfterPrime Systems
PAID PLUGINS IN THE SUITE
If you like the Event Bus architecture, the paid plugins follow the same design:
- AP Timer Suite — Replicated Timers + Threshold Events ($14.99): AP Timer Suite - Replicated Timers | Fab
- AP Cooldown Suite — Replicated Cooldowns ($24.99): AP Cooldown Suite - Replicated Cooldowns System | Fab
- AP StatusFX Suite — Replicated Status Effects ($24.99): AP StatusFX Suite - Replicated Status Effects & Buff/Debuff System | Fab
All standalone, all server-authoritative, all Gameplay Tag-keyed, all Blueprint-first with full C++ access.
Let me know if you have questions or run into anything. I’ll keep this thread updated with changes.
— Michael / AfterPrime Systems
