## 2 Related Work  
One could claim that SVREs have (or have not) been widely used and studied. Thus, the particular research and evaluation results of this subject area could (or, again, not) please some learning stakeholders, especially if it is considered as under investigation. In our query for existing literature reviews, we discovered fifteen relevant publications synthesizing results from previous empirical studies. The characteristics of these reviews are summarized in Table 1.  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Reference** & **Reviewed Articles (Vears)** & **Subject** & **Level of Education 1 ** & **Mode** & **Focus** \\ \hline [PERSON] and [PERSON], 2010 [28] & 15 (2001-2007) & All & K-12 and HE & All & Educational uses, research methods, topics, and findings \\ [PERSON], 2011 [29] & 55 (1982-2009) & All & All & All & Institutional effectiveness of digital simulation games \\ [PERSON] and [PERSON], 2011 [30] & 53 (1999-2009) & All & All & All & Educational contexts, pedagogical approaches, features, and outcomes \\ [PERSON] et al., 2011 [31] & 27 (2003-2010) & All & K-12 and HE & All & Educational uses, research methodology, \\ [PERSON] and [PERSON], 2011 [32] & 47 (2000-2009) & All & All & All & Methodological and theoretical trends around social and group phenomena \\ [PERSON] et al., 2012 [33] & 100 (1990-2011) & All & All & All & Taxonomy of educational uses, research trends and gaps \\ [PERSON] and [PERSON], 2013 [34] & 107 (2006-2011) & All & All & Chronological trends, research focus and characteristics \\ [PERSON] et al., 2014 [35] & 62 (1990-2013) & Health & HE and PE & All & Characterize and categorize \\  & & & & application areas & identification of key components for \\ [PERSON] and [PERSON], 2014 [36] & 35 (2000-2013) & Teacher Training & HE and PE & All & effective teacher training \\ [PERSON] et al., 2014 [37] & 67 (1987-2011) & All & K-12 and HE & All & Effect and impact of instructional design principles \\ [PERSON] et al., 2017 [38] & 167 (2000-2015) & All & All & All & Design and research trends, positive and negative effects \\ [PERSON] et al., 2017 [39] & 50 (2000-2016) & STEM & K-12 and HE & All & Effectiveness, design, affordances and theoretical underpinnings \\ [PERSON] et al., 2018 [40] & 205 (2003-2016) & All & All & All & Classification of learning affordances and activities \\  & & & & & Game-based learning features, instructional models, effectiveness, benefits and challenges \\ \hline \end{tabular}
\end{table}
Table 1: Summary of reviews on Virtual Worlds in an educational context.  
The majority of the previous literature reviews on 3D virtual immersive environments in education had examined multiple levels of education [28; 41], including primary, secondary, tertiary, higher, and professional education (PE) and focused mainly on attendance-based applications [30; 37]. A minority (only three) had focused on specific fields [35; 36; 39]. Despite its distinctiveness from school education [42; 43], no review was conducted exclusively for finding out about social virtual reality environments' use or virtual worlds in higher education settings [44]. Moreover, there is no systematic examination of SVREs in the distant, online mode of delivery in any level of education. At that time and to the best of our knowledge, relevant studies to examine the effectiveness of SVREs in open and distance mode higher education were not available. The current study aims to address this gap by focusing exclusively on the missing or under-investigated aspects of learning with the use of SVREs.