  Cloud Gaming is an emerging service that catches growing interest in the
research community as well as industry. While the paradigm shift from a game
execution on clients to streaming games from the cloud offers a variety of
benefits, the new services also require a highly reliable and low latency
network to achieve a satisfying Quality of Experience (QoE) for its users.
Using a cloud gaming service with high latency would harm the interaction of
the user with the game, leading to a decrease in playing performance and thus
frustration of players. However, the negative effect of delay on gaming QoE
depends strongly on the game content. At a certain level of delay, a slow-paced
card game is typically not as delay sensitive as a shooting game. For optimal
resource allocation and quality estimation, it is highly important for cloud
providers, game developers, and network planners to consider the impact of the
game content. This paper contributes to a better understanding of the delay
impact on QoE for cloud gaming applications by identifying game characteristics
influencing the delay perception of users. In addition, an expert evaluation
methodology to quantify these characteristics, as well as a delay sensitivity
classification based on a decision tree is presented. The ratings of 14 experts
for the quantification indicated an excellent level of agreement which
demonstrates the reliability of the proposed method. Additionally, the decision
tree reached an accuracy of 86.6 % on determining the delay sensitivity classes
which were derived from a large dataset of subjective input quality ratings
during a series of experiments.
