The first build proved the visual thesis: photoreal splat capture, streaming and rendering at 30 FPS on an integrated GPU. That was always the falsifiable bar. But it played like a tech demo. It looked great and felt dead. A game is heard, seen, and felt, and I'd shipped one of the three.
What won back the most ground wasn't any single channel. It was the pairings. Two things arriving together did more than four arriving alone.
Collision is the clearest case. It used to be a thud and a haptic pulse. Now a single impact fires five things at once: the thud through the SFX bus, coloured by the per-arena surface so ROOM hits duller and LUDLOW brighter; a whole-mix low-pass that drops the cutoff to 500–2000 Hz and recovers over a couple of seconds; a screen-space blur pulse on the same envelope; the haptic pattern through the gamepad and mobile vibrate; and a marker on the replay event log so a future export can title the moment.
None of those are expensive on their own, and none are loud on their own. But every input you give is met by three or four channels of output that all agree on what just happened. That's what reads as responsive.
The thing that made the pairings cheap was a tiny impact-events bus: a few lines of pub/sub that emit an event with the normalised force. The blur, the low-pass, the replay recorder all subscribe on their own, none of them knowing about the others. The pattern repeats anywhere one event has several downstream reactions.
The harder judgement is when not to pair. Photo mode flashes a shutter but plays no shutter sound; adding one made the moment busier without making it better. The brake punch pairs with a brake-heat shimmer but no grind, because most cars stopping in most of these arenas don't make that sound. The rule I settled on: add a channel when its absence would feel like a missing tooth, not just because the slot is open.
It's a small discipline, and it changed how everything after it got built. When the drift model landed, the haptic, the toast, and the replay tag arrived in the same commit. When the out-of-bounds reticle landed, the compass needle and the audio cue waited until they had something to say. Do that consistently and the whole thing starts to feel deliberate instead of assembled.