# Immersive Tools in Engineering Education--A Systematic Review
## 3 Results
### Studies' Content Analysis  
In Figure 3, the articles' geographical distribution is presented, in addition to the STEM field under study. Some articles focused on one particular field (i.e., engineering, represented in orange), while others were a combination of two or more fields (i.e., science, technology, engineering, and math, represented in red). The country with the highest number of articles is the United States of America [20; 21; 22; 23; 24], followed by Mexico [25; 26; 27; 28], the United Kingdom [29; 30], and Nigeria [31; 32]. This systematic review encompasses works from 20 countries, showing that these tools are widespread. In Figure 4, it is possible to observe the distribution of published papers by year; 2023 and 2024 were the most recurrent years, with a total of six articles, followed by 2020, with five, and 2021, with four. Articles prior to 2020 were added through snowballing techniques. Figure 3: Studies’ geographical context. Figure 2: PRISMA flow diagram, adapted from [PERSON] et al. [17]. Figure 7 shows that Unity was the most used game engine [21; 26; 30; 31; 34; 35; 38; 40; 41; 43; 46; 47; 49], especially for VR applications, with six out of thirteen VR-based games developed using this engine. Out of those thirteen, four did not specify the game engine [29; 32; 33; 48]. A significant proportion of the serious games were developed using virtual reality [23; 24; 29; 31; 32; 33; 40; 41; 42; 43; 45; 46; 48], 3D [20; 22; 25; 30; 34; 36; 38; 39; 50], and augmented reality [26; 27; 28; 35; 44; 47]. Some studies employed combinations of immersive technologies, such as VR/AR [21; 49] and 3D/VR/AR [37]. On the other hand, for 3D environments, the engines were more diverse, which can be attributed to the use of existing games or game software to develop their own serious game. Only four of the six AR-based articles explicitly stated the Unity game engine [26; 35; 44; 47]. Some immersive tools require specialized hardware beyond standard computers or mobile devices. For example, VR typically uses head-mounted displays (HMDs) to enhance user immersion in a digital scenario. Figure 8 depicts several combinations and possibilities of HMD use, reporting the standard-use models. Figure 6: STEM areas and fields. Figure 7: Engines used to develop serious games. The most used models were HTC Vive (HTC VIVE PRO [42] and HTC VIVE [41]) and Oculus Rift [40,45]. Microsoft Hololens 2 [21] and Cave Automatic Virtual Environment (CAVE) TM [14] were the least frequently used devices. CAVE is a VR system that utilizes large projection screens in a closed room. The screens usually display a 3D, high-quality, immersive scenario. The CAVE TM system, in turn, relies on four back-projection display screens, stereoscopic and synchronized image rendering, and magnetically tracked 3D input devices. The physical dimensions of the CAVE system are 304 cm \(\times\) 304 cm \(\times\) 274 cm [23]. In the VR/AR category, one article used Microsoft HoloLens 2, and another did not specify what type of HMD was used. The article under the 3D/VR/AR category does not specify the head-mounted display (HMD) type used. Of all 16 articles with VR, 10 do not specify what kind of HMD was used [24,29,31,32,33,37,43,46,48,49]. Training effectiveness and student feedback were also analyzed; it was concluded that their assessment used subjective and objective methods for both parameters, though Table 1 reflects a higher use of objective tools such as questionnaires, quizzes, and tests. Subjective methods, including questionnaires, interviews, and structured feedback, were preferred to assess participants' feedback, as seen in Table 2. Some points raised by the participants' experience with the serious games were related to the immersion feeling, graphics quality, SG usefulness, user-friendly experience, engagement, motion sickness, dizziness, and learning outcomes.