## 3 Materials and Methods
### Trace Anonymization
It is because some of the server-to-client packets aggregate information such as a set of items or plenty of players, whereas client-to-server packets are dominated by the most frequent player activities. Indeed, the most outstanding 44 bytes long packet was about player move in our measurement. It is noteworthy that these findings are consistent with previous research conducted on PC MMORPG [11]. Despite the difference between wired connection and wireless connection, such a particular game genre that requires a strongly synchronized setting shows a similar traffic pattern. This may also indicate that the robustness of mobile networks has helped game developers safely assume robust connectivity between game client and game server. Game \(B\) exhibits similar patterns in both client-to-server and server-to-client traffic: (1) client-to-server traffic is characterized by a small number of dominant packet types closely tied to player behavioral patterns, and (2) server-to-client traffic displays a longer-tail distribution. Figure 2 displays the packet length distributions for both types of traffic. It is important to note that these graphs include HTTP headers, resulting in overall packet lengths that are greater than those observed in games using direct TCP sockets (i.e., Game _A_). Considering the difference, Figure 1(a) demonstrates the prevalence of specific packet lengths, such as those around 500 bytes, similar to what was observed in Game \(A\). ### Inter-Packet Arrival Times within a Session

We conducted an analysis of inter-packet arrival time as it serves as a valuable indicator of game developers' expectations regarding the robustness of the mobile network. Initially, we classified the collected network traffic by player session ID and subsequently calculated the inter-packet delay for each direction within each player session. For Game \(B\), which uses request-response-style HTTP, we calculated a timestamp for each response according to a matching request timestamp, load-balancer delay, and server processing time. Figures 3 and 4 present the distributions of inter-arrivals computed through this process. In the case of the MMORPG-style Game A, we observe remarkably short inter-packet arrival times (Figure 3). Approximately 99.6% and 99.5% of measured inter-arrival times fall within the 1000-millisecond threshold for both client-to-server and server-to-client traffic, respectively. This observation implies that the game places a high level of expectation on the quality of wireless network connectivity, irrespective of whether it is through mobile networks or Wi-Fi. This pattern is similar to those of PC games of the same genre, i.e., continuous interaction with players. Figure 2: Packet lengths distribution for Game \(B\) (single-player puzzle). Lengths also include HTTP headers. Thus, the graphs show the lengths of data in TCP payload. Meanwhile, in both directions, very long tails are revealed despite their short average inter-arrival times. Further analysis of packet types attributes this pattern to application wake-ups after extended periods of inactivity. This behavior is common among mobile applications, including games that frequently encounter interruptions and resume operations. Game \(B\) also exhibits relatively short inter-arrival times in Figure 4. A significant 87.2% of the traffic falls within the 10,000-ms threshold. Notably, even when considering server processing time in the calculation of each response timestamp, the difference in distributions of requests and responses remain nominal. Given the gameplay patterns typical of puzzle games, the presence of 10-s inter-arrival times in each direction is notably short. Also, the distributions show a long tail similar to Game \(A\). This implies that a mobile device's usage pattern has a significant impact on a mobile game's inter-packet arrival time, which was not observed from PC online games.