multiplayer-networking.md

Multiplayer Networking Guide

This guide covers OpenQ4 multiplayer networking behavior and the cvars used to tune or revert prediction/lag-comp behavior.

Quick Summary

• Server-side hitscan lag compensation is enabled by default.
• Remote-client prediction runs in enhanced mode by default.
• Both systems can be switched back to legacy behavior with cvars.

CVar Reference

Setting	Default	Range	Scope	What it does
net_mpLagCompensation	1	0..1	Server gameplay	Enables server-side lag compensation for multiplayer hitscan traces.
net_mpLagCompMaxMS	200	0..1000	Server gameplay	Caps rewind window in milliseconds used by lag compensation.
net_mpLagCompBiasMS	0	-200..200	Server gameplay	Adds/subtracts additional rewind bias in milliseconds.
net_mpLagCompDebug	0	0..2	Server gameplay	Debug logging for lag compensation (0 off, 1 summary, 2 verbose).
net_mpPredictMode	1	0..1	MP client prediction	Selects remote-player prediction mode (0 legacy limited, 1 enhanced per-frame).

Legacy Compatibility Switch

Use this to restore legacy multiplayer behavior:

seta net_mpLagCompensation 0
seta net_mpPredictMode 0

Recommended Starting Presets

Default Internet Play

seta net_mpLagCompensation 1
seta net_mpLagCompMaxMS 200
seta net_mpLagCompBiasMS 0
seta net_mpPredictMode 1

Low-Latency/LAN

seta net_mpLagCompensation 1
seta net_mpLagCompMaxMS 80
seta net_mpLagCompBiasMS 0
seta net_mpPredictMode 1

Notes

• Lag compensation applies to authoritative multiplayer hitscan traces on the server.
• net_mpLagCompDebug output is intended for server diagnostics and tuning.
• Tune net_mpLagCompMaxMS before using large net_mpLagCompBiasMS offsets.