Abstract In this study we propose an approach to assess the fear of heights through a 3D virtual reality environment. We show that an immersive scenario provides a suitable infrastructure to such purpose, when supported by related behavioural and physiological measurements. Our approach is grounded in the principled framework of constructed emotions. This allows to shape fear detection as a case of categorical perception, which is amenable to be formalised as an unsupervised learning problem. Meanwhile, it paves the way for addressing meaningful physiological parameters for the assessment. Gauging fear of heights in individuals, beyond its theoretical relevance, is cogent for the early discernment of workers who are unsuited for operating at altitude and who may require to undergo specific training or, eventually, to be recruited for different positions.

In story-driven video games, such as Role-Playing Games (RPGs), a static and repetitive interaction with Non-Player Characters (NPCs) can negatively impact fun and immersion. On the contrary, an NPC able to show emotions and endowed with a personality that matches its behavior can keep the user engaged for a longer time. Unfortunately, this aspect has not yet been fully investigated. We propose Moody5, a preliminary solution designed to help game designers create “personality-biased” agents able to interact in sensible ways in the framework of interactive storytelling. In particular, it supports the creation of agents that exploit the Goal-Oriented Action Planning (GOAP) technique to reach their goals but whose chain of actions and quality of the interaction with the player are dynamically affected by personality and emotions. To obtain this result, we have borrowed ideas from the Big Five theory [1] and the Emotion Facial Action Coding System (EMFACS) by Ekman & Friesen [2]. We validated the proposed solution in a narrative test scenario inspired by the Harry Potter universe. Our preliminary survey demonstrated that Moody5 could improve the gameplay experience and replay value while providing a helpful Unity plugin for game developers.

Training agents to play in contemporary multiplayer actions game is a challenging task, especially when agents are expected to cooperate in a hostile environment while performing several different actions at the same time. Nonetheless, this topic is assuming a growing importance due to the rampaging diffusion of this game genre and its related e-sports. Agents playing in a multiplayer survival first person shooter game should mimic a human player, hence they should learn how to: survive in unexplored environment, improve their combat skills, deal with unexpected events, coordinate with allies and reach a good ranking among the players community. Our aim has been to design, develop and test a preliminary solution that exploits Proximal Policy Optimization algorithms to train agents without the need of a human expert, with the final goal of creating teams composed only by artificial players.

This short paper presents the second international workshop on Games-Human Interaction - GHItaly 2018. The goal of this series of workshops is to focus on advanced aspects of the design and development of game interfaces. The quality of the resulting interaction is a highly relevant issue for creating an engaging and satisfactory user experience, especially when deeply multidimensional artefacts such as video games are concerned.

In recent years we are witnessing an increasing interest of young players in Multiplayer Online Battle Arenas (MOBAs). In a MOBA, two or more teams compete for resources on a limited map with real-time interactions. In order to achieve the required level of coordination, network performances must offer to each player an adequate and uniform Round Trip Time (RTT) to the game server. Unfortunately, different ISPs will give different RTTs based on technical and commercial settings. In this paper, we define an overlay network to convey all the team traffic through the teammate with the lowest end-to-end delay to the game server. By doing so, we leverage on the peering between ISPs, usually offering better performances due to commercial agreements, to obtain an homogeneous and bounded delay for all team members. The proposed solution has been tested using the popular game League of Legends. In this paper preliminary, and promising, results are presented.

One of the most profitable and emerging high-tech markets is the one that involves games for PC and consoles; a market that is growing year by year and that is rapidly evolving. Several big game corporations are implementing now the remote video streaming through the domestic network between two devices; a feature that regards not only PCs but also consoles. This paper investigates one of the main services of this type, the Steam In-Home Streaming, to analyze the generated network traffic when considering different types of game. Gathered data can help to understand whether this type of service can actually be supported by today's regular Internet connections.

In these last few years we are witnessing a tremendous change in the way video games are developed. On the one hand, large development teams with a multi-layered organisation are employed. On the other hand, we see an increasing request for online services and functionalities. Combining these two trends together usually results in large projects involving parallel and distributed systems. Despite the adoption of team-oriented source code and asset repository managers, code testing and debugging is still left to human direct management. In particular, distributed debugging is a complex problem due to the synchronisation required between network nodes to correctly reconstruct the sequence of events leading to a malfunctioning feature. To solve the aforementioned problem, we designed and implemented DREAD: an architecture to support distributed debugging in real-time games. When adopting our architecture, developers will record events on edge systems, collect them on a centralised sync, and then consolidate everything in a synchronous way. Following this approach, it will be easily possible to detect unexpected software behaviours and trace back to their causes.

In the last few years we have witnessed a tremendous change in the way game developers are required to deal with software production.We moved from small groups building the application ground-up to large coordinated teams with hierarchical organisation.To support this transformation, game developers are now using integrated development and execution environments called game engines.Among all possible gaming platforms, mobile ones are proving to be a challenging ground due to their intrinsic requirement for game engines to deploy the final application on a distributed system.In this paper we discuss about requirements for next-generation game engines for mobile devices.In particular, we propose a variation of the standard approach for game engines architecture pushing from a monolithic architecture toward a distributed one.In our solution, the mobile game engine becomes modular and lower the distinction between client and server side.

Among the many uses of Artificial Intelligence techniques in video games, one particularly relevant from the perspective of the entertainment of the player is the ability to mimic believable behaviours in non-playing characters for first-person-shooter games. In our opinion, the solutions commonly adopted in the industry could be improved by simulating decision making under condition of incomplete information. To tackle this aspect, we propose a perspective approach that pairs behaviour trees to a simplified Publisher-Subscribers communication pattern.

In this paper, an approach and a rubric for measuring commitment to computer-supported collaboration in student teams is presented.

In these last few years we are witnessing a change in the way video games are implemented. Starting from an early age, where a single developer was sometimes in charge of the whole creative process, we have moved now toward extremely large groups with a multi-layered organisation. This increasing complexity of team organisation, together with a tremendous growth of projects size, calls for the adoptions of development approaches leveraging on scalability and distributed computing environments. Unfortunately, today's development and execution environments for games (usually called game engines) are suffering from a number of architectural constraints. As a result, we strongly believe current engines will not be able to provide the flexibility and scalability required by game developers of the next generation. To overcome the above limitations, in this paper we propose SMASH (Stackless Microkernel Architecture for SHared environments): an architecture where a game engine is decomposed in several dynamic and independent software modules interacting via a microkernel-like message bus. Game modules can just be inserted, debugged, and removed from a running engine once its internal messaging protocol is clearly defined. Moreover, following this approach, game modules can be dynamically dislocated on multiple machines to obtain a truly distributed, scalable, and fault-resilient system where adaptation can be achieved mostly without downtime.

The market penetration of in-home entertainment systems is playing a crucial role in the diffusion of interactive multimedia services. In this context, thin-client game systems have received a lot of attention, shifting the computational burden of the game play toward the server while the client renders a fat video stream. This paper proposes an analysis of the network characteristics of the Remote Play for PlayStation 4 and PlayStation Vita, providing some insights on the network dynamics of this system under different game types. The measurements involve video games of different genres, analyzing the bitrates, the packet size, capturing the dynamics of the whole streaming session. Results indicate that the service generates a large quantity of big packets downstream and smaller and lesser packets upstream. Gathered data can help to understand if this type of service could be offered through the today's normal Internet connections.

This paper investigates one of the main game streaming services, the Steam In-Home Streaming, to analyze the generated network traffic. Gathered data can be used to model this type of traffic in simulations and to determine whether it could be supported by Internet connections around the world.

In this paper we focus on mobile data offloading and propose a solution for the placement of offloading infrastructures that optimizes the trade-off between reducing deployed resources and increasing traffic breakout. We base our analysis on a real dataset of Internet accesses generated, in the city of Milano, by some 50,000 users of an important mobile network operator. The target application we consider is the distribution of digital contents (such as MP3 songs, videos and newspapers) over an urban area. The paper's contributions is showing that offloading of digital contents can be achieved by leveraging people's regular mobility patterns.

ABSTRACT The mobile revolution has brought us the possibility to enjoy our favorite applications anywhere and anytime. In this context, interactive games over mobile networks embody a fascinating case study both for their commercial success and for their technical challenges, thus, sparking interest and development. The current state of the art of interactive games over mobile networks is captured in this article. We discuss main requirements and analyze possible combinations of existing solutions to provide better support for highly interactive game sessions with mobile players. Copyright © 2012 John Wiley & Sons, Ltd.

In these last years, we have assisted to a skyrocketing diffusion of Massively Multi-player Online Role-Playing Games (MMORPGs) and Massively Multiplayer Online Games (MMOs or MMOGs). In these environments, which are complex socio-technical distributed systems, a huge amount of players interact to have fun and develop their characters. Looting Systems (LSs) help allocating valuable in- game objects, as fairly as possible, among the participating players. The medium/long term effects of the adoption of different Looting Systems on players have not yet been adequately investigated, in spite of the fact that they could impact heavily on players' satisfaction and hence on their "fidelity" to a specific game service. In the present work, we simulate the impact of several LSs on different players base, offering hints for reflection and further investigation to MMOs developers.

In these last years the growing availability of personal mobile devices has boosted the demand for mobile services offered based on location and context. Mobile gaming services are, of course, no exception. Unfortunately, the 3G networks infrastructure struggles to keep pace due to scalability limitations and a pull-based service model. One feasible solution, also for gaming, is to adopt an Opportunistic Network (ON) to exploit unplanned contact opportunities between players to perform data exchange and forwarding in ad hoc mode. When designing a game for an ON, the main issue is about forecasting the feasibility of a given gameplay when applied to a real - and complex - environment. In this paper we address this issue proposing an opportunistic game that is meaningful for the category of collaborative puzzle games. The game is evaluated by means of simulations on the topology of a real city in order to understand its scalability and setback on the gameplay.

In the last decades mobile phones have evolved into powerful devices able to bring Internet services into our pockets. Following this trend, a popular application as gaming has extended its domain from home computers and consoles to the mobile realm. Indeed, mobile games embody a successful application for smartphones able to engage millions of subscribers worldwide. The next step is the creation of a new generation of mobile games, representing more than just a tiny version of home entertainment blockbusters; the ubiquitous use and the interesting features (i.e., camera, gyroscope, connectivity, GPS, etc.) of mobile phones create unprecedented opportunities for completely new kinds of gaming experience. As a proof of concept, we have created an application for mobile phones exploiting their camera and connectivity as available in every modern smartphone to digitally replicate and enhance an outdoor game for children that would not be playable through a desktop PC.

With the recent evolution of network-based multiplayer games and the increasing popularity of online games demanding strict real-time interaction among players - like First Person Shooter (FPS) -, game providers face the problem to correlate network conditions with quality of gaming experience. This paper addresses the problem of the estimation gameplay quality during real-time games; in particular, we focus on FPS ones. Current literature usually considers end-to-end delay as the only important parameter and deducts system performance indexes from graphical ones. Player satisfaction, on the other hand, is usually evaluated in a subjective way: asking the player, or measuring how long he/she stays connected. In this paper we use a testbed with synthetic players (bots) to directly correlate network end-to-end delay and jitter with expected players' satisfaction. Running extensive experiments we argue about effective in-game performances degradation of penalized players. Performances are measured in terms of score and number of actions kills, actually - performed per minute.

The AS-level Internet topology has shown significant clustering features. We propose a new set of clustering metrics and conduct extensive measurement on the AS- level Internet topology. We give a thorough characterization on the clustering features and their evolution. We also study the clustering features of different topological structures by comparing the Internet with various topology models. Due to the limitation of existing topology models on capturing clustering features, we design a new topology model based on clustering. Through extensive evaluations, we claim that our model can closely capture the clustering features as well as other common topological properties.

Multicast solutions have been evolving from "bottom" to "top", i.e., from IP layer (called IP multicast) to application layer (referred to as application layer multicast). Recently, there are some new proposals (named as overlay multicast) using certain "infrastructure" (composed of proxies) in the middle. Although it is well accepted that application layer multicast and overlay multicast are easier to deploy while sacrificing bandwidth efficiency compared with IP multicast, little research has been done to systematically evaluate and compare their performance. In this paper, we conduct a comparative study of different types of multicast routing protocols. We first present a qualitative comparison of three types of protocols, and then we provide a quantitative study of four representative protocols, namely, PIM-SSM, NARADA, NICE, and POM by extensive simulations. Our studies will help to answer some of the most important questions, such as which way to go: top, bottom, or in the middle?.

IP multicast confronts a severe scalability problem when there are large numbers of multicast groups in the network due to state explosion and control explosion. In backbone networks, this state scalability problem is exacerbated, since there are potentially enormous multicast groups crossing backbone domains, in this paper, we propose a scalable protocol, called BEAM (bi-directional aggregate multicast), which uses the concept of aggregated multicast. BEAM is a distributed protocol using bi-directional trees. It is simple and easy to implement. Through simulations, we show that BEAM can greatly improve state scalability with very low overhead: up to 98% state and tree setup and maintenance overhead reduction with less than 0.14 bandwidth waste in our experiments.

In this paper, we measure and model the distribution of multicast group members. Multicast research has traditionally been plagued by a lack of real data and an absence of a systematic simulation methodology. Although temporal group properties have received some attention, the location of group members has not been measured and modelled. However, the placement of members can have significant impact on the design and evaluation of multicast schemes and protocols as shown in previous studies. In our work, we identify properties of members that reflect their spatial clustering and the correlation among them (such as participation probability, and pairwise correlation). Then, we obtain values for these properties by monitoring the membership of network games and large audio-video broadcasts from IETF and NASA. Finally, we provide a comprehensive model that can generate realistic groups. We evaluate our model against the measured data with excellent results. A realistic group membership model can help us improve the effectiveness of simulations and guide the design of group-communication protocols.

Source specific multicast (SSM) is a viable solution for current multicast applications, since the driving applications to date are one to many, including Internet TV, distance learning, file distribution, streaming media, etc. It brings many benefits in billing, address allocation, and security. However, SSM still confronts the serious state scalability problem when there are a large number of simultaneous on-going multicast groups in the network. We propose a protocol to improve the state scalability of source specific multicast, which is called aggregated source specific multicast (ASSM). We design the detailed ASSM protocol and show that our solution can obtain significant multicast state and tree management overhead reduction while achieving transparency to end-users, compatibility with existing multicast technologies and low overhead.