Serious games : supporting occupational engagement of people aged 50 + based on intelligent tutoring systems

This paper offers an overview of the requirements of serious games to support occupational engagement for people at age 50 and above, and the features for such a serious game. A comprehensive literature revision and a questionnaire to 23 active in the field health professionals of the Valparaiso region (Chile) were performed. In the end, among the various requirements stated, primary requirements were the evaluation of adaptation skills and organizing space and objects skills as well as of information exchange skills and coordination skills, with respect to occupation-based interventions and routines within a social context. Afterwards, some primary features were stated, such as the use of intelligent tutoring systems, adaptability, difficulty balance, real-time strategy, non linear stories, and spatial, temporal and adversaries reasoning. In the discussion about the features, issues of purpose, strategy and the personalization of a serious game for people aged 50 and older were specified in detail.


INTRODUCTION
Serious games, that engage users and contribute to achieving well-defined and more significant purposes than pure entertainment [1][2], have considerably increased their capabilities in recent years.A serious game is defined as "a mental contest, played with a computer in accordance with specific rules, that uses entertainment to further government or corporate training, education, health, public policy, and strategic communication objectives" [3].Serious games as such were started to be applied in training, for example, in battle simulations for military training [2,4].Most of them have been developed from techniques and methods proposed in the last century [5][6].Recently serious games are increasingly incorporating computational methods that can process information and profiles tailored to the interests of people 50 years and above, and potentially improve the use of existing technologies to support therapeutic intervention practices.In fact, as the elderly population is steadily growing, the labor force participation of the next generations will decrease for the labor supply, dramatically affecting the future development of national economies and productivity.
The promotion and protection of health is essential for human welfare and sustainable socio-economic development.In Chile, the old age dependency ratio (which is the ratio of the number of older dependents -people at an age when they are generally economically inactive -, i.e., aged 65 and over, compared to the number of people of working age, i.e., 15-64 years old) will increase between 2025 and 2050, from 33.3 to 51.1, respectively [7].Most of the development and promotion programs are driven by public policies that are implemented through various agencies, both public and private services that depend on Ministry of Health, Municipalities, Compensation Funds and the autonomous community work groups.In 2010, the Valparaíso region had the greatest age dependency ratio in Chile, with 71 elderly for each 100 people under the age of 15 years old [8].Furthermore, projections for year 2020 show that Valparaíso will be the most aged region where the number of elderly would be greater than that of the young population.
There has been an increasing recognition that occupation plays a central role in health and well-being.One of the main problems is the lack of technologies for interventions for occupation aimed at people 50+ that are perfectly functional.In general, technological instruments apply to people who have disabilities, and need health care facilities with a high cost associated, rather than the promotion of healthy lifestyles of people, to protect conditions for life outside work, and reduce the risk elements to reach the retirement age.Therapists attempt to implement instruments, at lower cost than health care, maintaining and developing the occupation with sufficient activity and autonomy in older people to reduce the likelihood of disease at an acceptable cost.Furthermore, therapeutic interventions lead to strengthening the capacity of older people to participate and share their own experience.Process and playing oriented activities are nutritious and enriching experiences, and engage them for many purposes.Among others, achieving and discharging more energy, gaining balance, moving from an existential state to another or getting only pleasure from it.Process-oriented activities such as games can lead to changes in lifestyle of people after age 50 [9].Especially, when games increase awareness, it is possible to change or redesign people 50+ lifestyle.These activities include experiences in which risks are present in decision making processes, whether in the physical, mental or spiritual realm [10].Nowadays, serious games have the potential to maintain the quality of life and productivity of older people.This paper promotes this approach by contributing with an overview of the requirements and features of serious games for interventions for people 50+, relying on a comprehensive literature revision and a questionnaire to health professionals of the Valparaíso region.

SERIOUS GAMES FOR PEOPLE 50+
The emergence of the study of games as discipline goes back to Game Theory [11].The performance of basic algorithms ("minimax") that model a game problem between opponents to decide a better play, can be improved by reducing the state space to be examined ("alpha-beta pruning").
A mathematical model that has extensively been used in games is Finite State Automata (FSA) that date back to the 1950s.Finite state automata FSA approaches ( [12][13]) can describe the system behavior in terms of input and output events that occur to a game character, and change the current state of the game.That is, world events may force a change in the state.A FSA describes the output events produced depending on the state of the FSA (Moore model) or the inputs and state (Mealy model).FSA can be represented using different notations: state transition diagrams, state transition matrices, "if-then-else" scripts, etc. [14] A technique that is typically used in the development of serious games is Pathfinding, which calculates the movements of a player character and nonplayer characters using heuristic search methods such as A* [15], which depends on the game domain information to find the least-cost path to a solution.Other steering techniques estimate the local movements of the solution neighborhood for route finding [16].
The making of programs that learn to play board games started with the application of reinforcement learning algorithms, which are based on the analogy of animal learning that shows how animals can learn arbitrary sequences of actions by only maximizing rewards: Q-Learning, Temporal Differences TD, etc. [17][18][19].In recent years, techniques such as Monte-Carlo Tree Search MCTS [20][21] have successfully been applied to computer games.Under certain conditions these algorithms have been shown to adapt their behavior [22].Adapting serious games refers to model behavior, difficulty levels and scenarios according to the player's abilities, so that the behavior is sufficiently challenging, the difficulty levels are balanced and the scenarios are of interest to the player.In general, adaptability in games [23] means that the visual and audio contents of the game are either customized by evaluating parameters and semantic information (e.g., to indicate to the game about the obstacles or difficulties that can be used with the decision-making of a player), or related to events produced by the interaction with the user.The latter consists in the ability to either provide automated game balancing (off-line mode) or to adjust to its players as they play (on-line mode), concurrently.Moreover, it is mandatory an architecture of techniques and methods for game adaptability to ensure adherence to serious games.
Users define their characteristics in order to adjust the interventions to their cognitive limitations, in order to evaluating their progress to enable them to advance in difficulty levels [24].
Here we present a classification of serious games on the basis of the distinction between (1) physiotherapy games, (2) cognitive-perceptual games, and (3) socio-emotional games.

Physiotherapy Games
Serious games have recently been implemented as therapeutic environments of virtual reality [25][26] for physical rehabilitation.The use of this kind of therapy has increased mainly due to the low cost of equipment such as Nintendo Wii [27].Also, depending on the content of health care and the data obtained from user interaction, mobile games have been proposed for rehabilitation [28].Physiotherapy games can provide learning experiences based on approaching the user with a closer representation to a digital simulation environment [29][30].The design of 3D physiotherapy games has been facilitated considerably by the use of game engines [31], which in some cases can continuously adapt the game flow [32].We can distinguish serious games that either run according to difficulty levels that user must overcome [33], or behave like open worlds [34].
"Exergaming", that combines exercise and video games to reduce sedentary lifestyles and improve health, have been developed, incorporating technologies that track the movement and physical activities [35][36].Some are based on geolocation to increase physical activity, allowing people to play a game according to their position [37].

Cognitive-Perceptual Games
Serious games for cognitive stimulation and training have recently been researched and developed, in order to reduce the deterioration of executive functions [38][39].Cognitive-perceptual games have been applied to either stimulate executive functions or recover after a stroke [40][41].Thus, serious games can stimulate cognitive development and meet the needs of entertainment allowing the setting of a continuous interaction between the player's actions and responses from the computer, encouraging active participation and controlling the execution of the proposed activities for players.
Cognitive-perceptual games can be supported by techniques of production systems and goal-oriented action planning.Rule-based or production systems are integrated in cognitive architectures, i.e., models that mimic human reasoning, such as SOAR [42].With appropriate technology of optimized rules matching, some games may operate in real time with more than one million rules.
Real-Time Strategy, RTS, [43][44][45][46], which is typically found in games where players build armies to attack bases, is applied to problems of micro and macro management for planning and strategies generation [47][48].RTS multiplayer games suffer from state explosion when handling requests for pathfinding of various players [49], especially in massively multiplayer online role-playing game, MMORPG [50].
Multiplayer games with ranking systems [51] incorporate statistical estimation methods to calculate the relative skill levels of players (for example, the ELO rating system).Additionally, other methods can identify and track the skills of players in a game mode to match them in batches of competition [52].
Cognitive-perceptual games that include spatial, temporal and adversaries reasoning [53] (e.g., video games where multiple players compete for resources and typically make decisions into 2D worlds [54]) use techniques of log data mining, evolutionary algorithms, reasoning under uncertainty and constraint programming.Techniques for spatial reasoning in serious games and their effects are discussed in [54][55][56].
Most cognitive training games that are currently marketed are designed for use to maintain or improve executive functions such as attentional control and memory.

Socio-Emotional Games
The production, design and usability of socioemotional games facilitate communication be-tween multiple users, including social interaction, communities and chat, and to keep in touch with close contacts [57][58][59].
Socio-emotional games such as RPG (Role-playing games) usually engage seniors in terms of emotional experiences.A subset of these games are First person shooter (FPS) and Third-person shooter games (TPS or 3PS) [60][61].Several RPG games typically led to a real-time progress that combines interesting plots with different characters on appealed stories.
For RPG, non-player characters (NPC) are the adversaries and assistants in a game.The behavior of a NPC is the subject of considerable concern for using computational intelligence techniques in computer games.The identity of a NPC has become important in serious games such as MMORPG.Whether a character is either inherited by a player (well formed and attractive) or built from "scratch", the player will be "committed" to the game for learning a game (acting) and select, initially in terms of behavior, a character immersed in human social models.Decision trees [62][63], are structures that can describe the NPC behavior in a game or to determine who wins the game.Decision trees are typically implemented using if-then-else scripts.Furthermore, NPCs are usually driven by story and narrative in games.
In socio-emotional games based on narrative, the stories can be broken down into modules that communicate through events and resources associated with patterns [64].Machine learning techniques, story grammars, planning and problem solving (Case-Based reasoning) have typically been used in this case [65][66].Some approaches describe the behavior of characters and dialogue from system logs (logging) that keep trace of the user interaction [67][68].It is noted that these methods require too many resources for development, adjustment and testing of general criteria and should be strongly modified and specialized for a specific game to obtain acceptable results.In Creatures [69], character behavior can be learned over time using neural networks and genetic algorithms.Resilient backpropagation, Rprop, is the learning method used for neural networks in games that offers the best performance [70].
One of the biggest challenges is dealing with socioemotional games based on non-linear stories [71][72][73][74].For example, extracting stories over character arcs can be based on an abduction-based framework structured as constraint handling rules CHR with stored constraints expressed as temporal relations, etc. (while not goal oriented, [75] leads to discover narrative events via abduction by using weights on emotions related to the stories).

Requirements
With respect to the requirements for serious games for interventions of people 50+, where requirements are defined as something that is desired or needed, a study by [76] reveals that their motivations to play computer games were "to escape from reality, to stay in touch with society, and to give meaning to the day, and most have no need for multiplayer gaming".This study shows that a great difficulty with computer game play was "the overall and in-game speed, which mostly cannot be adjusted to age-related abilities".Likewise, a research by [77] shows that the key user requirements that interest older people are: challenge, socialization, fun, providing learning opportunities, and escape from daily routine.It is considered that serious games have higher barriers for learning than traditional computer applications when older people try to memorize story elements [78].Moreover, improving the quality and quantity of digital content for people 50+ is very significant in an increasingly connected society to extend their self-worth, with focus on health promotion activities, environmental adjustment, self-care and training in the different aspects of the intervention process.
The intervention process facilitates engagement in occupation related to health and participation [79].A well defined intervention plan can be supported by serious games.The intervention plan describes the types of interventions and is developed based on the results of the evaluation process to accomplish the purposes of a person 50+.The types of interventions include (a) Purposeful activity, (b) Consultation process, (c) Education process and (d) Occupationbased intervention activity.Purposeful activity consists in the use of occupations and activities of a person to train behaviors, within a therapeutic environment.In the Consultation process practitioners use their knowledge and experience to collaborate with a person, in organizations, institutions or groups.The Education process provides knowledge and information about occupation, health, and participation as training in a particular simulated occupation or activity.Finally, Occupation-based intervention activity consists in the therapeutic use of occupations and real activities of a person, who engages in client-directed occupations that meet the identified goals.
The practitioner can assess the enhanced ability of a person 50+ to handle performance skills that enables commitment to the intervention goal.Performance skills, defined by Fisher [80] as observable, concrete, goal-oriented actions a person uses to engage in daily life occupations, can be effectively executed in activities using computer games.Among the multiple descriptions and categorization for performance skills, Fisher proposed the following: (a) motor skills, (b) communication/interaction skills, and (c) process skills.Motor skills consist in moving and interacting with task, objects, and environment, and include aspects of energy, strength and effort mobility, posture, and coordination.Communication/ interaction skills convey intentions and coordinate social behavior to act together with people, and include physicality, relations, and Information exchange.Process skills are used in managing and modifying actions while completing a task, and are comprised of energy, knowledge, temporal organization, organizing space and objects, and adaptation.
Recent studies [81] have shown that greater social participation in older people diminish their cognitive decline.Performance skills are influenced by several conditions of the environment within and surrounding the person.Context can be external to the client (physical, social, virtual); internal to the client (personal, spiritual); and may have external characteristics with beliefs and values that have been internalized (cultural context), and also may include a temporal dimension.
Context influences performance patterns that develop over time.While accomplishing occupations or activities, an individual adopts habits, routines, and roles.Habits such as dominating, useful and impoverished habits refer to specific, automatic behaviors.Routines are established sequences of occupations or activities that provide a structure.Roles are sets of behaviors assumed by society and may be defined by the client.
In summary, the literature revision shows that the revealed requirements correspond to the following aspects: (1) types of interventions, (2) performance skills, (3) motor skills, (4) communication/ interaction skills, (5) process skills, (6) context, and (7) performance patterns.We will follow these aspects in the rest of the paper.

Features
To this end serious game must be equipped with a set of features, defined as distinctive aspects, qualities, or characteristics, helping and allowing persons aged 50 and older to develop appropriate activities.
The use of serious games that maintain the physical health of elderly has been categorized based on technology, user interaction and usability criteria [82].Similarly, [83] suggests focus areas that serious games must achieve for rehabilitation: purpose, user interface, game dimension, single-player to multi-player, adaptable challenge, progress known by elderly and monitoring.For educational purposes (e-learning) and to improve human kinetics, treatment environments have great potential to support the management of the daily life of the people 50+ [84].However, serious games that are relevant to rehabilitation are not adapted to the entertainment, and those that conform to gameplay are not suitable for rehabilitation [85].
For the maintenance of a certain level of cognitive skills for this domain [86], the most important features are spatial, temporal and adversaries reasoning, planning and strategies generation, ranking systems.RTS effects in older adults are analyzed in [87][88].
Automated tools based on models and languages for interactive narrative are considered very suitable for the people 50+.To participate in socio-emotional games, people 50+ can relate their own memories to the contents of game story.
A very important feature is content customization of personalized serious games that depends on the user profile (for example, using clustering techniques).In this sense, serious games store and adopt user information, as well as provide difficulty levels based on the results of the players performance.Similarly, authoring and producing personalized digital content with its own capacity to adapt to different platforms, e.g., for mobile games promoting healthy lifestyles [89].On the other hand, serious games with the support of semantic processing are used to demonstrate achievement of the intervention objectives [90].

PRE-BACKLOG OF REQUIREMENTS
The increasing interest in serious games is due to its potential to make learning more attractive and to maintain performance skills in o people 50+.There is a need for a review of the requirements with regard to serious games for the intervention plans of people 50+.We are now at the first stage to establish a backlog of requirements from groups advocated to this domain of the Valparaíso region.We report a pre-backlog of requirements from health professionals of the Valparaíso region that will mostly be embracing serious games by means of a questionnaire.

Method
In the setting of the pre-backlog of requirements, we used a questionnaire.For the respondents, the selection sample included practitioners from the Valparaíso region having expertise in working with people 50+.These health professionals were specialists in kinesiology, psychology, occupational therapy and phonoaudiology.They work in public or private health institutions at the Valparaíso region.The general configuration, participants and procedure of the questionnaire are discussed in the following.
The respondents were invited to participate in a questionnaire through the contact points responsible of a therapy group working on this domain.
The questionnaire was administered to 23 practitioners of the Valparaíso region who work with people 50+.To accomplish this we contacted a list of professionals that met these requirements.
The questionnaire (see Table 1) consisted in 8 closed-ended questions, with multiple options to the participants that refer to the aspects of types of interventions, performance skills, motor skills, communication/interaction skills, process skills, context, performance patterns, and usage of computer games in interventions.We bring to mind that these aspects are relevant in conformance to the literature.Before applying the questionnaire, we validated it with occupational therapists.The questionnaire was made available in a web site.The analysis of the questionnaire allows us to establish whether the requirements do satisfy or not the situation of the Valparaíso region, where serious games are not commonly used in interventions.

Questionnaire to practitioners
In this part we discuss the results of the questionnaire to practitioners of the Valparaíso region that work with people 50+.Among all the performance skills in activities using computer games, one common requirement emerged: process skills.We note that practitioners identify that process skills can better develop and maintain occupation for people 50+ during performance (see Figure 2).On the contrary, motor and communication/ interaction skills are less considered by practitioners.Among the process skills (see Figure 3), practitioners envision that there is a need to evaluate, above all, aspects such as preventing the adaptation (i.e., ability to anticipate, correct for and benefit by learning from the consequences of errors that arise in the course of task performance), and organizing space and objects (i.e., skills for organizing task workspaces and objects).Although evaluating motor and communication/interaction skills is less considered by practitioners, here we observe that practitioners make the point of the importance of evaluating the coordination aspect, i.e., using more than one body part to interact with task objects in a manner that supports task performance (see Figure 4), as well as the information exchange aspect (see Figure 5).
Figure 6 describes the percentages of responses that designate the positively influence of con-texts, in which activities using computer games occur.We note that the social context is indicated as best suited to perform activities for people 50+.
According to the percentages of respondents that indicate the better performance patterns adopted in activities in Figure 7, using computer games by people 50+, we observe and the trend is that routines are suitably adopted in intervention plans.supporting interventions plans for people 50+.We start with a brief discussion about the results of the questionnaire, and then we discuss the way to engineering the questionnaire results to features for serious games aimed at the application area.

Global discussion
When comparing the questionnaire results, we note some appealing contrasts in the results.In other words, for intervention plans that include computer games for people 50+, practitioners give importance to evaluating process skills on a social context, but on the other hand aspects of communication/ interaction skills are not considered relevant.A reason of this fact may be that practitioners are aware of the increasing availability of computer games for cognitive training (a marketing trend which is not our research concern) or may do not know another kind of computer games.
Additionally, we observe that a context generated by the presence of persons, groups, and organizations that surround the person after age 50 do receive more attention by practitioners than the performance on physical or virtual contexts.On this matter, the construction of a virtual 3D environment or the way that the game is played may not be a demand for a serious game, but the production of the circumstances in which the social context can influence some activity in the intervention process, as well as the routines, by practitioners in collaboration with the client.According to this perception we deduce that enabling the creation of these conditions may permit to exploit the effective application of serious games in their intervention.We will proceed to describe the mapping of the questionnaire results discussed to features in the following.

Transforming questionnaire results to features
In this part we discuss the way to map the questionnaire results to features for serious games Figura 8. Usage of computer games.
In Figure 8 the percentages of respondents are shown that indicate the use of computer games in the intervention process.

SPECIFYING THE FEATURES
From the results obtained of the combination of evidence of practitioners and the literature revision, we specify the main features for serious games for people 50+ in intervention processes.Here we focus on (A) purpose of the serious game, (B) its strategy, and (C) its personalization.
A) Purpose: In conformity with [78], the questionnaire applied to practitioners expresses that their requirements primarily pertain to assess process skills of elderly within a social context.In this regard, the questionnaire also expresses that their requirements pertain to indicators on process skills of adaptation (that is, anticipating errors, profiting by learning) and organizing task objects and spaces (that is, gathering tools and materials, searching).
On the other hand, since the social context is fully related to information exchange skills (that is, giving and receiving information within an occupation), we may consider that as a feature for the domain of people 50+, the purpose of a serious game should be to manage and assess both process skills as well as communication/ interaction skills.B) Strategy: With respect to the strategy, we observe that a serious game with a purpose of assessing process skills and communication/ interaction skills within a social context should take into account cognitive and real-time strategies, as well as spatial, temporal and adversaries reasoning.According to literature, as long as routines for the maintenance of cognitive abilities are important, we may consider a serious game with as strategy a micro management of planning generation, i.e., a mission for a singleplayer game or a non linear story that enables the socialization.To enhance the performance of such skills for consultation and education processes, a serious game may be an effective educational method that provides a safe environment for trial and error, and immediate feedback to the user.
C) Personalization: According to literature, serious games must be adapted to the user profile, in activities that are consistent with the difficulty levels to achieve the best results.A possible implementation may be the use of adaptability [91], pervasive narrative [92], and difficulty balance [93], for controlling the execution of the proposed skills and encouraging the active participation of the client.With regard to profile definition, we may consider serious games with adjustment of parameters obtained by computer vision and a voice recognition system connected to sensor networks, where parameters may be the objects and sounds associated with the social context.A possible implementation may be intelligent tutoring systems based on personalized web with rich social interactions, using deductive logic or narrative models, which have proved to be effective in achieving learning outcomes [94].

CONCLUSIONS
In this paper we made inquires about serious games for interventions for people over age 50.In particular, we made inquires about the requirements of serious games for this selected domain and the features for these serious games.In our approach, we realized a comprehensive review of literature, and realized a questionnaire to 23 health professionals of the Valparaíso region concerned with therapeutic interventions.We stated some requirements, primarily the maintenance within a social context of process skills as well as communication/interaction skills, with respect to routines and occupationbased interventions.Afterwards we stated several features that concern primarily the application of computational methods for intelligent tutoring systems, difficulty balance, real-time strategy, non linear stories, spatial, temporal and adversaries reasoning.When analyzing the features, we specified the criteria of purpose, strategy and personalization of a serious game for this particular domain.
For future work, additional studies may expand the geographic coverage in data collection because most of the health professionals that work on this particular domain are mainly located on the Area Metropolitana region.Considering the relative growth of the aging population, this work addresses a topic of high social and economic impact.

Figure 1 .
Figure 1.The most used types of interventions.

Table 1 .
Questionnaire on requirements of serious games for interventions for people over age 50.