## 1 Introduction  
Augmented reality (AR) is an emerging technology that supplements reality and allows the user to experience the real world with virtual objects superimposed on or composed with the real world [1]. One of the key advantages of AR is that it is available on most of today's smartphones and tablet devices, which makes it more available to a wider population of users [2]. Mobile AR has already proven its potential in various application areas, such as retail/shopping, interior design, tourism, navigation, training, education, healthcare, military, video games, and others [3]. As an emerging technology, it enables new forms of human-computer interaction compared to traditional mobile solutions and provides users with engaging experiences, which has a positive impact on users' motivation to use AR-based solutions. This is especially recognized in the field of game-based learning, as learners nowadays require new and more interesting learning experiences [4]. The concept of games that are not played primarily for amusement, but to impart specific knowledge or skills to the player, is known as \"serious games\" and was first coined by [PERSON] in 1970 [5]. According to [6], the term \"serious games\" should be used for games explicitly designed for purposes other than entertainment, i.e., they can be seen as having a specific purpose and not as a synonym for other existing applications. Over the years, serious games have experienced growth, especially in domains of education, training, well-being, advertisement, cultural heritage, interpersonal communication, and healthcare [7]. Serious games can be considered effective educational tools when applied in education properly and in a student-centred way, which is considered one of the key features of the new generation of students [4]. AR-based serious games have also proven their potential to increase student interest and influence motivation and learning efficiency [8; 9]. Great interest has also been shown in the field of inclusive education, where research can be found focusing on the design of serious games for a wide range of students with disabilities. However, the development of such solutions is still more focused on a specific difficulty or disability, without applying the principles of Design for All [10]. To benefit all learners, serious games must be developed to meet the needs of a wide range of users, including users with disabilities. This is especially important for AR-based serious games which involve different interactive tasks with virtual content in the real environment, such as those identified in [11]. Intuitive and user-friendly interfaces are also critical for the successful implementation of AR in educational contexts [12]. Thus, AR-based solutions are extremely suited for exploring the best ways of interacting with the user depending on their needs, limitations and context, i.e., to make them more accessible as there are still many accessibility challenges that need to be addressed [13; 14]. Accessibility is a measure of the extent to which a product, service, or environment is suitable for all users, including people with disabilities and the elderly. When considering users with disabilities, accessibility can be considered a great part of usability, as it is defined as the \"extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use\" [15]. It can generally be achieved by applying the principles of Universal Design (UD), which is a design method that aims to integrate the needs of people with disabilities and the elderly into products intended for widespread use. Besides addressing accessibility needs, UD addresses the needs of all people to the greatest extent possible, without the need for adaptation or specialized design [16], including people with different ages, sizes, abilities or disabilities.