User Experience in Digital Games: Development and Technical Evaluation of Interactive Interfaces

Enzo Rocha dos Santos; Ana Paula Françoso

DOI: 10.22167/2675-6528-202602865

Article derived from a Course Conclusion Work (TCC), with content based on the student’s original work and adapted to the editorial format of the E&S Magazine with the support of the ResumeAI tool, an artificial intelligence solution developed by Instituto Pecege for textual synthesis and organization.

Summary

The research investigated the application of User Experience (UX) principles in the development of digital game interfaces, considering the relationship between human-system interaction and technical performance. The study addressed the problem of how interface and architecture decisions can influence the predictability of interactions and system efficiency. The objective was to analyze how interface and interaction architecture decisions could influence the efficiency and predictability of system behavior in digital games. To this end, an instrumental case study was developed, of an applied nature and comparative approach, based on two versions of a playable prototype in Unreal Engine 5: a Base version and a version with enhanced UX. The versions maintained the same scenario, mechanics, and objectives, while the changes focused on the interface and interaction architecture. The evaluation was carried out through technical usability criteria, based on Nielsen’s heuristics and Norman’s principles, a standardized task flow, and technical metrics obtained with Unreal Insights. The enhanced UX version presented a 44.6% reduction in initial loading time, a 28.4% reduction in average object interaction time, an increase in average FPS from 89 to 120 frames per second, and a reduction in average latency per frame from 11.2 to 8.3 ms. The results indicated technical gains associated with interface and architecture interventions, although the subjective impact on the player’s experience still requires user validation. It was concluded that the integration of UX principles, interaction architecture, and technical instrumentation constitutes a viable approach for evaluating and refining digital game prototypes.

Keywords: Software Engineering; User Experience; Game Interfaces; Prototyping; Usability.

1. Introduction

The gaming market in Brazil has shown accelerated growth, with a 177% increase in the number of game development studios between 2018 and 2023, according to data from the Brazilian Association of Electronic Game Developers and ApexBrasil (2023). Furthermore, the country ranks as the tenth largest global gaming market, generating 2.7 billion dollars in 2022 (Newzoo, 2022). This expansion scenario highlights the growing importance of the player experience in digital game development, where the organization of layouts, menus, and visual and auditory feedback mechanisms are crucial for the interaction between the player and digital interfaces.

From this perspective, digital games are complex interactive systems implemented in software, encompassing multiple subsystems for graphical rendering, operational logic, and physics (Gregory, 2018). The interfaces and interaction flows within these systems establish communication between the player and the system, addressing issues of software engineering and interaction quality (BNDES, 2016). Unlike a purely aesthetic perspective, this interaction can be evaluated by usability criteria, such as clarity, predictability, and efficiency (Nielsen, 1993; ISO 9241-210, 2019). User-centered design, in turn, considers the characteristics, needs, and limitations of people in the development of interactive systems (Norman, 2024), allowing User Experience (UX) to be incorporated to structure interaction and guide decisions regarding software interface and behavior.

In the initial stages of digital game development, technical evaluations are fundamental to identify interface problems before end-user testing. UX evaluation approaches in games can combine usability criteria and domain-specific methods to identify problems during the development process (Mylly et al., 2019; Desurvire; Wiberg, 2009). Early identification of UX problems allows for the refinement of interaction decisions before later validation stages (Hodent, 2017). In this context, aspects such as effectiveness, predictability, and error prevention are essential elements in the analysis of human-system interaction (Nielsen, 1993).

The evaluation in this work was limited to a technical stage prior to user testing, focusing on the observation of technical aspects of the interface and system behavior. This delimitation allows for an investigation into how UX decisions can be incorporated into the development process and evaluated through technical criteria and performance metrics. Mechanisms such as affordances, feedback, and mapping are important for communicating to the user the possibilities for action and the system’s responses (Norman, 2024). User experience, therefore, can be analyzed by technical criteria and performance metrics during the development cycle (Nielsen, 1993; Norman, 2024; ISO 9241-210, 2019; Hodent, 2017).

High entry barriers, such as excessive control complexity or the absence of clear interaction cues, can hinder the initial understanding of the system. The concept of Game Approachability addresses the reduction of initial complexity and the progressive organization of mechanics, aiming for a more predictable and balanced learning curve (Bernhaupt et al., 2015). From this perspective, digital games are interactive systems structured by rules, events, and states that regulate the communication between player and software. Each user action triggers internal routines that process the input and generate perceptible responses in the interface or game environment (Schell, 2019). This chain of input, processing, and response is central to the interactive experience, influencing the clarity and predictability of the implemented mechanics.

Game design, therefore, is not limited to the creation of challenges, but also to the coherent organization of interaction structures, integrating visual, auditory, and tactile elements to favor the understanding and fluidity of the experience (Swink, 2008; Rogers, 2010). The organization of interface elements and control systems should allow the player to understand their action possibilities and receive adequate feedback, contributing to the perception of control during the game (Swink, 2008; Rogers, 2010). User experience spans different stages of development, from technical conception to empirical validation. The use of game engines, such as Unreal Engine, allows incorporating user-centered design principles from the initial project phases through prototyping, system instrumentation, and technical evaluation of interactions (Bond, 2014). Features like Blueprints, UMG, and Unreal Insights in Unreal Engine 5 allow implementing interface mechanisms, logging events, and analyzing system behavior during execution (Bond, 2014).

Considering the problem of how interface and interaction architecture decisions can influence the efficiency and predictability of system behavior in digital games, and the need to technically evaluate these decisions in early development stages, this work proposes the development and comparative analysis of two versions of the same interactive game system, a Base Version and a UX Version, keeping the scenario, mechanics, and objectives of the prototype equivalent. The evaluation is carried out through technical usability criteria based on Nielsen’s heuristics and UX principles, a standardized task path guided by cognitive walkthrough principles, and performance metrics obtained directly from the game engine. It seeks to investigate how interface and interaction architecture decisions, understood as event structure, processing flows, and feedback mechanisms, can influence the efficiency and predictability of system behavior in digital games.

2. Material and Methods

The research was characterized as applied in nature, with a comparative and predominantly quantitative approach in the technical evaluation stage. The adopted design was that of an instrumental case study, with the empirical object being the development and analysis of a playable digital game prototype. This prototype was developed in Unreal Engine 5 (UE5) and investigated through the comparison between two versions: a Base Version and an enhanced UX Version.

Both versions of the prototype maintained equivalence regarding the scenario, mechanics, and fundamental objectives of the game. Interventions were concentrated on the organization of the interface and the interaction architecture. The study did not involve participant recruitment, manipulation of variables on subjects, or measurement of subjective responses, focusing on a technical and exploratory comparison of system performance.

For the prototype design, two playable versions were developed in Unreal Engine 5. The Base Version was conceived with a minimal functional interface, without the systematic application of advanced usability principles. Its interface elements, menus, and interactions were designed to ensure basic system operation, without optimizations related to clarity of actions, feedback, or visual organization.

In contrast, the UX Version was developed from the deliberate application of usability principles described in the literature. Explicit visual affordances, immediate feedback to user actions, consistent mapping between controls and effects, and visual organization oriented towards interaction predictability were incorporated. Strategies were adopted to ensure response times below 400 ms, with optimizations in the event architecture and interaction processing, using Doherty’s threshold as a reference for perceived fluidity (Doherty; Sorenson, 1982).

The Base Version interface was implemented through the UMG system and visual programming with Blueprints, including a main menu, a simplified HUD, and a basic system for interaction with objects in the scene. The main menu consisted of essential navigation actions, implemented directly, without the use of dynamic visual feedback or additional perceptual reinforcements, limited to the basic functionality necessary for the system’s operation.

The interactive logic of the main menu of the Base Version was structured from basic UMG system events. The menu initialization occurred through the “Event Construct” event, responsible for activating a simple ambient audio. The actions associated with the Start and Exit buttons were implemented directly, triggering the loading of the main game level and the application shutdown, without additional mechanisms for visual, auditory feedback, or state confirmation.

The character interaction system in the Base Version was initiated from a player input event, which triggered a “Line Trace By Channel” function from the camera for detecting interactive objects. After detection, sequential validations of the object’s existence and the implementation of the interaction interface were performed. Interactive actors corresponded to the classes “BP_Item” and “BP_Door”.

The enhanced UX Version was developed from the Base Version’s functional structure, incorporating interventions to improve interface clarity, interaction predictability, and communication between player and environment. The modifications focused on the technical restructuring of interfaces, interaction flows, and system response architecture, based on usability heuristics, cognitive walkthrough, and performance metrics obtained from the game engine.

To ensure comparability, the Enhanced UX Version utilized the same UE5 technological platform, the same visual assets, and an identical functional scope. Modifications were exclusive to interface elements, feedback, control mapping, and event architecture. A perceptual feedback mechanism was implemented for item collection, triggering an audible cue and visual reinforcement in the interface to confirm the action.

The organization of the main menu interface in the UX Version was structured based on principles of human-computer interaction, such as Hick’s Law (Hick, 1952) to reduce decision time. The sizing and positioning of buttons considered Fitts’s Law (Fitts, 1954). The interface incorporated visual and auditory microinteractions, such as color changes, scaling up on hover, and sound cues, acting as immediate perceptual reinforcements.

A progressive visual feedback was introduced for interactive items in the scene, using two concentric collision volumes. The first volume acted as an initial proximity detector, triggering a discrete signal, while the second enabled direct interaction, displaying the necessary action key. This approach established a hierarchy of detection, proximity, and interaction states.

The technical implementation of visual feedback was based on Post-Processing Materials, using the engine’s “Custom Depth Stencil Buffer” to render the outline directly in the rasterization pipeline. From a software architecture perspective, constant state checking was replaced by an Event-Driven system, using UE5’s “Event Dispatchers”, updating the graphical interface only when notified of changes in the game model.

The interface evaluation was conducted through three complementary procedures. Firstly, a technical interface analysis was performed, using Nielsen’s heuristics as criteria to identify improvement opportunities in the Base Version and guide changes in the UX Version. Aspects such as system status visibility, consistency, error prevention, and recognition rather than recall (Nielsen, 1993) were considered.

Secondly, a cognitive walkthrough was applied, defining task scripts representative of the interaction with the system. This procedure allowed for the analysis of the clarity of necessary actions, the number of attempts, execution time, and the predictability of interface responses. A formal heuristic inspection with multiple evaluators or severity classification was not performed.

Finally, a technical metrics analysis was performed, where objective data was collected through UE5 instrumentation tools, specifically “Unreal Insights”. This tool allowed the collection of objective data related to response time, interaction events, navigation flow, and interface performance at runtime (Bond, 2014).

To enable the objective analysis of user-system interaction efficiency and predictability, a technical instrumentation strategy was adopted, focusing on measuring the time between the player’s action and the system’s perceptible response. The interaction flow was structured through input, processing, and response events, implemented in the prototype’s Blueprints. The instrumentation of these points allowed for the recording of temporal information associated with the main interactions.

The evaluation procedure was structured into a six-sequential-task roadmap, allowing for systematic measurement of each interaction stage. The tasks included: Initialization and Loading; Interface Navigation and Configuration; Proximity Exploration and Detection; Collectible Object Interaction; Scenario Element Interaction; and State Monitoring and Finalization. The standardization of the stages allowed performance measurements to be extracted at identical moments in both prototypes.

3. Results and Discussion

This section details the research findings, comparing the performance and efficiency of interactions between the Base Version and the enhanced UX Version of the digital game prototype. The central objective was to identify the impact of interface design and interaction architecture decisions on user experience, evaluating how the systematic application of User Experience (UX) principles can influence technical system metrics. The results obtained provide subsidies for understanding the relationship between interface interventions and interaction predictability, as well as the operational efficiency of the system, as outlined in the study methodology.

Initially, the analysis focused on the prototype’s loading time, a critical factor for the initial perception of system agility. The Base Version presented an initial loading time of 5.6 seconds, while the enhanced UX Version demonstrated a significant reduction to 3.1 seconds. This improvement represents a decrease of approximately 44.6% in the time required for game initialization. Although the absolute difference of 2.5 seconds may seem moderate, this gain is attributed to the refinement in resource organization and system initialization, including the optimization of interface element loading through “Blueprints”, with the implementation of “lazy loading” and “event-driven” on-demand execution strategies, avoiding unnecessary initializations and reducing the initial processing cost.

Beyond loading time, the speed with which the system responds to player actions during interactions with the environment is fundamental to the quality of the experience. To evaluate this aspect, the average response time of interactions with objects present in the scenario was analyzed. A reduction in the average response time for interactions with scenario objects was observed in the enhanced UX Version compared to the Base Version. This reduction corresponds to approximately 28.4%, indicating a substantial improvement in the efficiency of interactions between the player and the system. These results suggest that the modifications implemented in the interface and interaction architecture have contributed to making the system more responsive and predictable, reinforcing the importance of the structured application of UX principles in the development of digital games.

The recorded response time values remained below the threshold of 400 milliseconds, frequently cited in user experience literature as a benchmark for interactions perceived as immediate (Doherty; Sorenson, 1982). This consistency in system response directly contributes to maintaining the fluidity of the experience and user engagement. The heuristic evaluation of the main menu in both prototype versions revealed relevant differences in the criteria of option visibility, visual hierarchy, element consistency, and the presence of “feedback” mechanisms, according to Nielsen’s usability principles (1993).

In the Base Version, less clarity was noted in the visual hierarchy and an absence of explicit feedback mechanisms during interaction with the menu elements. In contrast, the enhanced UX Version incorporated visual and auditory interaction indicators, as well as a clearer hierarchical organization of interface elements. These improvements, which promote greater system state visibility and element consistency, translated directly into reduced interaction response times. The incorporation of visual “feedback” and “affordances” mechanisms, as advocated by Norman (2024), contributed to the predictability of actions, keeping response times below the 400 ms threshold.

The implementation of a progressive visual “feedback” system for interactive items in the scene in the enhanced UX Version was one of the central refinements. Each interactive object was surrounded by two concentric collision volumes, associated with different proximity states. The first volume acted as an initial approach detector, triggering a discrete signal, while the second enabled direct interaction, displaying the necessary action key. This approach established a hierarchy of states – detection, approach, and interaction – allowing the player to understand the possibilities of action before executing any command, unlike the Base Version, where interaction depended exclusively on trial and error.

To ensure visual “affordances” without compromising object geometry, a technical solution based on Post-Processing Materials was developed, utilizing the engine’s “Custom Depth Stencil Buffer” to render the outline directly in the rasterization pipeline. This technique ensured consistent visual signaling and constant processing cost on the GPU. From a technical standpoint, the system was implemented in an event-driven manner, using collision volume entry and exit triggers to activate visual state changes, avoiding continuous per-frame checks and contributing to system efficiency and interaction logic maintenance.

The refactoring of the software architecture, replacing constant state checking with an Event-Oriented system, was crucial. Using Unreal Engine 5’s “Event Dispatchers”, the graphical interface began to be updated only when notified of changes in the game’s “Model”. This change minimized CPU overhead, keeping the “input” response latency (“Input Lag”) consistently below 16 ms, a critical requirement for the feeling of fluidity. The Base Version, in contrast, used a continuous “polling” checking approach, consuming continuous CPU cycles to keep the HUD updated, even in the absence of changes in game data.

The enhanced UX Version, with its “event-driven” model, allowed the interface system to remain inactive most of the time, being triggered only by specific events, such as changes in the sanity variable or the detection of object proximity. This optimization reduced the consumption of computational resources, contributing to the maintenance of interaction fluidity, performance improvement, and preservation of responsiveness below the 400 ms threshold, without overloading the game’s other subsystems. The impact of the optimizations was also evident in the stability of performance during game execution.

The “framerate”, which represents the number of frames rendered per second, is a direct indicator of the interactive system’s fluidity and responsiveness. Fluctuations in “framerate” affect the response time of player actions and can compromise the predictability of interactions, given that each frame represents an update window of the game state (Gregory, 2018; Epic Games, 2024). The Base Version presented more significant performance variations due to continuous (“polling”) processes. In contrast, the enhanced UX Version maintained a more stable FPS and lower oscillation in rendering time, reinforcing the efficiency of the “event-driven” approach over the processing cycle.

Specifically, the Base Version registered an average FPS of 89 frames per second, while the enhanced UX Version achieved an average FPS of 120 frames per second. This substantial improvement in “framerate” contributes to what Swink (2008) calls “game feel”, increasing the player’s sense of control. Schell (2019) emphasizes that consistent action and “feedback” cycles depend on a stable update rate, which was more effectively achieved in the enhanced version.

In addition to the “framerate” analysis, the average latency per frame was also evaluated, demonstrating the efficiency of the system’s response time. The Base Version presented an average latency of approximately 11.2 ms per frame, while the enhanced UX Version reduced this value to about 8.3 ms. This reduction in system update processing time directly impacts the user experience, providing a more immediate response to player actions and influencing their perception of control and fluidity.

The observed improvements are not limited to isolated technical performance, but directly impact the user experience, according to Nielsen’s (1993) and Norman’s (2024) usability principles. FPS stability and latency reduction, combined with the event-driven architecture, increase the predictability of interactions, allowing the system to respond directly and contextually to user actions, avoiding unnecessary updates and inconsistent behaviors. This structured UX approach, therefore, is not limited to an aesthetic review, but constitutes a restructuring of the project’s interaction engineering, with the adoption of the “Model-View-ViewModel” (MVVM) pattern that enabled the decoupling between the game state logic and the graphical presentation layer, allowing for greater organization and control over interface updates.

In summary, the results demonstrate that the systematic application of User Experience (UX) principles in the development of digital game interfaces, through interventions in interaction architecture and interface design, resulted in measurable technical gains. The enhanced UX Version presented significant improvements in initial loading time, average object interaction time, “framerate”, and per-frame latency, indicating a more efficient, responsive, and predictable system. These findings reinforce the feasibility of integrating UX evaluation with software engineering practices from the initial prototyping stages, using the “game engine” itself as a development and instrumentation environment.

4. Conclusion

This work investigated how interface decisions and interaction architecture could influence the efficiency and predictability of system behavior in digital games. It was found that the systematic application of User Experience (UX) principles in interface development, through interventions in the interaction architecture and interface design, resulted in measurable technical gains. A significant reduction was observed in the initial loading time of the prototype and in the average interaction time with scene objects. Additionally, an increase was identified in the

frame rate

average and a decrease in average frame latency, indicating a more efficient, responsive, and predictable system. These improvements were attributed to the reorganization of the visual menu hierarchy, the implementation of

feedback

visual and sound, to the refinement of

action possibilities

of interactive objects and to the modification of the event architecture for an event-driven model, which contributed to maintaining response times below the 400-millisecond threshold.

The main contribution of this study lies in demonstrating that the integration of UX principles, interaction architecture, and technical instrumentation represents a viable approach for the evaluation and refinement of digital game prototypes in the early stages of development. However, the study presented important limitations, such as the absence of empirical user testing, which prevents us from stating that the changes produced improvements in player-perceived satisfaction or engagement. The use of Nielsen’s general heuristics, while adequate for technical analysis, did not fully encompass specific dimensions of the gaming experience. Furthermore, the comparison was conducted on a single prototype and in a specific development context within Unreal Engine 5, which restricts the generalization of the results. It is suggested that future studies complement this evaluation with user testing to validate the subjective impact of interventions, employ game-specific heuristics, and replicate the procedure across different genres and platforms to verify the consistency of the findings.

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