# Web-Based Serious Games and Accessibility: A Systematic Literature Review
## 1 Introduction  
The Web has changed the way people communicate and relate to each other. Technology has generated a continuous impact on society and individuals' behavior. The increasing access to the Web and the variety of devices that allow us to interact with it have made it possible for students to choose the tools and services that best suit their needs, and thus to personalize the learning experience [1].  
Figure 1 shows the Google Trends search related to web applications, serious games, and mobile applications made on the Web in the last five years. We found that the term serious games and web applications began to intensify from 2019.  
Serious games are \"games that do not have entertainment, enjoyment, or fun as their main objective\" (p. 21, [3]). The main objectives of serious games can be, among others, education, training, human resources management, and health improvement [4]. Web-based serious games constitute an area growing thanks to the improvement of browsers and technologies used on the Web [1], which have reduced the gap between desktop and web applications.  
According to Statista [5], the game-based learning market revenue worldwide between 2018 and 2024 indicates the serious games market is expected to grow from 3.5 billion U.S. dollars to 24 billion in 2024. The trend of serious web-based games has several benefits: (1) Reinforce learning in educational processes virtually and at a distance [1]. (2) Use the applications without the need to download, install, and configure. (3) Interact with the applications at any time and space. (4) Update the applicationautomatically with the latest version. (5) Use the applications with fewer technical problems due to software or hardware conflicts with other applications.  
Nowadays, there are many web-based serious games, but developers are not usually worried about making them accessible. The accessibility [6] aims to ensure that applications can be used by the maximum number of people, regardless of their abilities and regardless of the technical characteristics of the equipment used to access the application. According to the Web Content Accessibility Guidelines (WCAG) 2.1, some guidelines help validate web pages, applications including serious games, making them more accessible to everyone, including people with disabilities.  
This study compares articles related to accessibility in serious web-based games. In this research, we present a systematic literature review (SLR) [7; 8] that allows examining serious games' accessibility. We start from the following research question: What accessibility evaluation standards have been used by developers to create serious web-based games? This study defines the query strings that allow finding the most significant research related to accessibility in serious games [9]. To determine the query string, we apply the structure in terms of population, intervention, comparison, and outcome (PICO) [10].  
This SLR allowed us to (1) outline the issues relevant to serious web-based gaming and accessibility studies; (2) identify how accessibility is involved in serious gaming; (3) determine accessibility guidelines based on the WCAG, and (4) identify the assistive technologies and devices used to achieve accessibility in serious gaming according to disability. After an extraction process of 476 studies, a collection of 47 primary studies was selected using the Preferred Reporting Elements for Systematic Reviews (PRISMA) [11; 12], the flowchart in the selection process.  
This article is organized as follows. Section 2 introduces readers to the topic of accessibility and serious games. Section 3 describes the research method used for the systematic review of the literature. Section 4 includes the bibliometric analysis results and the literature review. Section 5 presents discussions of the results, along with limitations for research. Finally, Section 6 presents conclusions and future research work.