Note: Since “Z Legends 2 4.0.0” is not a publicly documented academic software release, this paper is a written in the style of a conference proceeding for software engineering or game systems. Z Legends 2 4.0.0: Architecture, Enhancements, and Performance Benchmarking of a Real-Time Multiplayer Action Framework John A. Sterling(^1), Mei-Lin Chen(^2), and Rajiv K. Sundaram(^1) (^1)Department of Game Engineering, Digital Futures Institute (^2)Networked Systems Lab, Asia Pacific University ABSTRACT This paper presents the complete system design and empirical evaluation of Z Legends 2 , version 4.0.0—a significant architectural milestone in the real-time multiplayer action game series. We introduce three core contributions: (1) a deterministic rollback netcode framework supporting up to 16 concurrent players with <50 ms latency compensation, (2) a dynamic Level-of-Detail (LOD) streaming system for seamless open-world transitions, and (3) a scriptable combat state machine that reduces input-to-action latency by 38% compared to the prior 3.x branch. Benchmark results demonstrate sustained 120 FPS on target hardware with a 12 ms server frame budget. We also discuss post-release stability metrics from 500,000 concurrent user sessions.

| Metric | 3.5.2 | 4.0.0 | Change | |--------|-------|-------|--------| | Load hitches (> 50 ms) per 10 min | 14.2 | 1.3 | -90.8% | | Average load time (new cell) | 212 ms | 68 ms | -67.9% | | VRAM usage peak | 3.1 GB | 3.4 GB | +9.7% |

– We did not test under packet loss > 5% or latency > 150 ms, where rollback frequency degrades gameplay. Also, deterministic simulation requires careful floating-point control – not all teams can implement this.

: Real-time networking, rollback netcode, game engine architecture, latency hiding, state synchronization. 1. INTRODUCTION The Z Legends franchise has been a benchmark for high-octane action combat since its debut. Version 4.0.0, codenamed “Chrono Shift,” addresses two long-standing challenges: deterministic state resynchronization under variable network conditions and scalable asset streaming for large environments. Unlike incremental patches, 4.0.0 introduces a refactored core loop, replacing the lockstep model of 3.x with a speculative execution framework.

– The 9.7% VRAM increase is acceptable given modern console/PC baselines (8–16 GB). Future work should implement adaptive LOD based on available VRAM.