Latency determines not only how players experience online gameplay but also how to design the games to mitigate its effects and meet player expectations.

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Latency and player actions in online games

The growth in the popularity of interactive network games has increased the importance of a better understanding of the effects of packet loss and latency on user performance. While previous work on network games has studied user tolerance for high latencies and has studied the effects of latency on user performance in real-time strategy games, to the best of our knowledge, there has been no systematic study of the effects of loss and latency on user performance. In this paper we study user performance for Unreal Tournament 2003 (UT2003), a popular first person shooter game, under varying amounts of packet loss and latency. First, we deduced typical real world values of packet loss and latency experienced on the Internet by monitoring numerous operational UT2003 game servers. We then used these deduced values of loss and latency in a controlled networked environment that emulated various conditions of loss and latency, allowing us to monitor UT2003 at the network, application and user levels. We designed maps that isolated the fundamental first person shooter interaction components of movement and shooting, and conducted numerous user studies under controlled network conditions. We find that typical ranges of packet loss have no impact on user performance or on the quality of game play. The levels of latency typical for most UT2003 Internet servers, while sometimes unpleasant, do not significantly affect the outcome of the game. Since most first person shooter games typically consist of generic player actions similar to those that we tested, we believe that these results have broader implications.

The effects of loss and latency on user performance in unreal tournament 2003

To support effective exploration, it is often stated that interactive visualizations should provide rapid response times. However, the effects of interactive latency on the process and outcomes of exploratory visual analysis have not been systematically studied. We present an experiment measuring user behavior and knowledge discovery with interactive visualizations under varying latency conditions. We observe that an additional delay of 500ms incurs significant costs, decreasing user activity and data set coverage. Analyzing verbal data from think-aloud protocols, we find that increased latency reduces the rate at which users make observations, draw generalizations and generate hypotheses. Moreover, we note interaction effects in which initial exposure to higher latencies leads to subsequently reduced performance in a low-latency setting. Overall, increased latency causes users to shift exploration strategy, in turn affecting performance. We discuss how these results can inform the design of interactive analysis tools.

https://idl.cs.washington.edu/files/2014-Latency-InfoVis.pdf

The Effects of Interactive Latency on Exploratory Visual Analysis

This paper presents the design, implementation, and evaluation of Colyseus, a distributed architecture for interactive multiplayer games. Colyseus takes advantage of a game's tolerance for weakly consistent state and predictable workload to meet the tight latency constraints of game-play and maintain scalable communication costs. In addition, it provides a rich distributed query interface and effective prefetching subsystem to help locate and replicate objects before they are accessed at a node. We have implemented Colyseus and modified Quake II, a popular first person shooter game, to use it. Our measurements of Quake II and our own Colyseus-based game with hundreds of players shows that Colyseus effectively distributes game traffic across the participating nodes, allowing Colyseus to support low-latency game-play for an order of magnitude more players than existing single server designs, with similar per-node bandwidth costs.

/pdf/colyseus-a-distributed-architecture-for-online-multiplayer-15q7qsfd57.pdf

Colyseus: a distributed architecture for online multiplayer games

In this paper we analyse different factors affecting players' perception and performance in multiplayer games. We introduce a mean opinion score metric borrowed from the subjective analysis of audio and video content to classify the player's perceived game quality. With a survey we investigated the player's view on network latency for a variety of games. Furthermore, we examine four different games under different network conditions and collect data on game score and subjective perception from every player. During the evaluation, we investigate the effect of latency and jitter on multiplayer games. We use regression analysis methods to identify coherences between delay, jitter, skill, game score, and the subjective impression of the player. Finally, we compare the results from the survey and the experiments.

Rory Coughlan

Papers

The effects of loss and latency on user performance in unreal tournament 2003

The effects of packet loss and latency on player performance in Unreal Tournament 2003