The Physics of Fear: Bridging Math to MetaSounds

TL;DR: We aren’t using random number generators to scare players. We are using a mathematical decay constant ($k=0.0012$) mapped directly to Unreal Engine’s MetaSounds and AI Behavior Trees.

The core manifestation mechanic in All Hallows is driven by a Vector DB Fear Profile. When the Aura AI decides to strike, it sends a ‘Manifestation Potency’ float to the server. But continuous float math is heavy, and we don’t want AI Behavior Trees ticking complex calculations every frame.

To solve this, we built a C++ bridge. The raw potency float is intercepted by the EchoProtocolAPI and mapped into a strict UENUM called EFearBracket (Calm, Unease, Paranoia, Psychosis).

Simultaneously, the C++ backend feeds this exact float into our audio engine. For objects like the Cemetery Door, the server replicates the potency to the client, which dynamically drives the MS_DoorCreak MetaSound parameters (Pitch, LFO Rate, and DecayHum). The fear is literally baked into the DSP.