Running head: A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 1 A Video Game Selection Process for Supporting Modding Projects

Most research & development (R&D) projects lack the financial resources to develop sophisticated VG-based training applications. Building on an existing VG resulting from a large development budget is a more frugal option. Although there are numerous examples of exploitation of VG in R&D projects, the selection process of these VGs and the possible modifications were rarely documented. First, this paper enumerates and classifies the possible forms of modifications and identifies the techniques for implementing these modifications in VGs. Then, it provides an example of a rigorous VG selection process for a R&D project on military training. The methodology requires identifying a set of VG titles that complied with a main criterion and then assesses them with other relevant criteria in order to determine the best candidate. Finally, this paper presents the architecture of a VG-based training system called ImPACT which implements a bio-feedback-driven gameplay. Sufficient details are provided so that other R&D projects may exploit a similar methodology in the future. Keywods: modding technique, modding form, mod. A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 3 A Video Game Selection Process for Supporting Modding Projects Video games (VGs) technology has continuously benefited of massive amount of investments over the last twenty years, the result being a significant technological improvement (www.dfcint.com). Virtual environments developed by open source community or by the industry for the scientific community pale into insignificance beside commercial VGs in term of functionality, graphic quality and content. Most research & development (R&D) projects or proof of concepts that require such advanced features do not have sufficient budgets to develop them from scratch. Modifying existing VGs resulting from large development budgets is a more frugal option. For instance, titles such as Unreal Tournament 3 (UT3) (2007) (www.unrealtournament.com) or Half-Life 2 (2004) (orange.half-life2.com) sequels provide various modification capabilities that make them suitable for prototyping or R&D. Although research teams possess some computer science knowledge, they often lack modding expertise that limits the exploitation potential of VGs. The risk of using an ad-hoc approach is high with the consequence being a lack of rigour. For instance, VGs that correspond to the theme studied could be rejected based on a false assessment of their modding potential. Another danger is to select familiar titles without undertaking a proper comparative approach. This article is indented for scientists and software development teams with generic programming background that desire to exploit VGs to conduct training or experiments. Guidelines to understand programming requirements and various forms and techniques of modding are provided. In summary, how VG should be selected and how can it be modified are the two important questions that this paper tries to answer. A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 4 This paper is divided into three parts. Part ONE presents possible options for modifying a VG. Part TWO introduces the methodology and applies it to a case study. This process identifies the VG title on which a Modwas developed. Part THREE presents the resulting architecture. Part ONE: Understanding the potential of modding. An overview of modding capabilities is necessary to better assess the modding potential a VG has to offer. Part ONE begins by enumerating and classifying possible forms of modification (modding forms) and then identifies techniques for implementing these modifications in VGs (modding techniques). Modding forms Inspired from Scacchi (2010), four forms of modding were retained and described under : (1) Graphical user interface (GUI) customization; (2) Content customization; (3) I/O customization and (4) Immersive customization. GUI customization. This common form adapts the GUI in order to optimize the player efficiency during the game experience. The three most common GUI changes are (1) the development of better information representations (Figure 1), (2) the addition of a head-up display (HUD) or overlay over the scene to support the realism of environmental constrains (Figure 2), and (3) the reorganization of widgets. 1 Modding and Mod refer to the action of modifying a VG and the modified VG itself respectively. A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 5 Figure 1: Example of better information representation extracted from VBS2 (www.vbs2.com). Figure 2: Example of HUD extracted from VBS2 Fires. The customization of external VG components, such as the mission briefing or after-action review summary, is considered as an extended form of GUI customization. These components provide user with relevant information both before and after the gameplay experience. Content customization. Content customization modifies one or many aspects of the VG contents such as in-game objects, terrains, textures, animations, lighting, sound, music, camera settings, artificial intelligence rules, scripted actions, gameplay rules, levels, maps, campaigns, shaders, etc. For instance, content customization inspired the Canadian Forces Army Learning Support Centre (www.armyelearning.ca) in the development of the VG-based training system Canadian Forces: Direct Action (2008), a mod of the popular VG S.W.A.T.4 (2005), where police officer textures were replaced by military ones. VG community (e.g. ModDB website (www.moddb.com)) provides numerous examples of modified VGs. I/O customization. I/O customization exploits external data to enhance game experience. This form was used by Dekker & Champion (2007) to develop a biofeedback-driven VG, where bio-sensing modifies the gameplay in real-time. Besides, I/O customization can support experimental analysis and after-action reviews sessions by tracking players' actions. Collected data helps to detect emergent problems, perform experimental analysis, and create a better A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 6 experience. For instance, the level of difficulty of a map could be adjusted by analyzing length of typical VG sessions. Immersive customization. This form emphasizes on enhancing a player’s sense of presence. Stereoscopic visualization, multiple displays and 3D surrounds sound are examples. Some products can adapt VGs to Virtual Reality (VR) displays. For instance, 3D Vision (www.nvidia.com) enables stereoscopic visualization for up to three (stereoscopic) displays. CaveUT (Jacobson & Lewis, 2005) and getReal3D (www.mechdyne.com) libraries succeeded in implementing this form of customization for advanced immersive systems exploiting off-axisrendering. Figure 3 summarizes modding forms by representing them in a generic VG architecture. Figure 3: Distribution of modding forms into a generic VG architecture. Modding techniques VG must support the required specific functionalities to allow modding. Moreover, skilled programming personnel are required, especially when the documentation provided by the A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 7 VG developer is insufficient or simply inexistent. A skilled workforce supported by proper “modding” guidelines can overcome programming challenges or limitations. For instance, customizing the GUI could be done by modifying scripts files on a given VG while it would require programming an external component on another one, with the same result for the player. Seven common approaches, called modding techniques, are described below: (1) Level editor, (2) Software development kits (SDK), (3) Scripting, (4) In-game command line console, (5) Configuration files, (6) File replacement and (7) Wrapper. Level editor. A level editor is a GUI software application able to design or modify levels, maps, and campaigns of VGs. Level editors assemble 3D objects together in order to create complex scenes to which apply behaviors and events. Level editors are sometimes included within the VG distribution or can be developed by a game community. In general, level editors are easy to use but mainly devoted to the graphical aspect of game content. For instance, UT3, Skyrim: The Elder Scrolls V (2011) (www.elderscrolls.com/skyrim) and Gran Thieft Auto IV (2008) (www.rockstargames.com/IV) supply VG editor tools to assist mod makers in their customizations. SDK and Scripting. SDKs and scripting techniques (e.g. UnrealScript (www.unrealengine.com/features/unrealscript)) offer the highest customization potential. Depending on the openness of the VG architecture, these techniques allow changing or enhancing VGs significantly. Since both approaches require programming and sometimes compilation, they offer more modding capabilities when they can be linked with third-party software. Overall, scripting is slightly less restrictive than SDK, even though there are scripting approaches offering high level of customization. A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 8 In-game command line console. This technique allows parameterizing of VG variables while the VG is being executed. Changes are made through a command line interface embedded into the VG. Examples of parameterization include VG avatars (e.g. speed, attack capabilities, stamina, artificial intelligence, etc.), VG environment (e.g.: lighting, seasons, physics behaviours, etc.), player experience (e.g.: HUD, VG gameplay rules, etc.) and computer system (e.g.: video resolutions, sound levels, network settings, etc.). In game command line console is often used for validating and testing effects of variable changes during the design process. Thereafter, retained changes are captured into VG configuration files. This kind of console could be found in Left 4 Dead (L4D) (2008) (left4dead.wikia.com/wiki/Console_commands). Configuration files. This technique allows parameterizing variables prior to the VG is launched. Changes are made by modifying scripted files included into the VG distribution. These variables are usually related to GUI and VG content. File replacement. File replacement technique consists in modifying or replacing files provided in the VG distribution, including 3D model files, textures files and sound files. It requires known and editable file formats, usually achieved via dedicated editors. Wrapper. This modding technique consists in intercepting any function calls to a specific software dynamic library by redefining the original version; when an application starts, a wrapper library is loaded instead of the original one. This modding technique can extend existing functionalities, including those related to sound and rendering. For instance, it could be used to add a post-rendering HUD to display debugging information, modify projection matrices in realtime to apply stereoscopic effect or manage multi-display rendering. The wrapper is exploited in VRGL and CaveUT libraries (publicvr.org). This technique has the advantage of not requiring any modifications to the VG. A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 9 Table 1 summarizes the seven modding techniques described above. Table 1: Modding techniques. Modding techniques Description Associated customization forms Examples Level editor GUI-based development. VG content customization (especially for graphics aspects). Animation, Levels / Maps, etc. Software development kit Various object-oriented programming forms (C++, C# ...) scripting forms (Phyton, LUA ...) or custom languages. All customization forms. GUI, Gameplay rules, Logs, etc. Scripting In-game command line console Functions called through a command shell interface embedded into the VG. All customization forms (exclusively for existing VG settings and variables). Configuration files Linear programming forms embedded in files. File replacement Modification or replacement of original file contents. GUI & VG content customization forms (done offline). Terrains / Objects, Sound / Music, Textures, etc. Wrapper Interception of function calls by creating software component that minics the the original one. Immersive & I/O customization forms. Stereoscopy, Off-Axis rendering, Heads-up displays, etc. Since there is no clear boundary between each modding technique neither a clear definition of what a level editor should do or not, it is difficult to identify the most adequate technique to achieve a customization form. A good understanding of the VG architecture capabilities is essential before committing time and resources to any modding techniques. A VIDEO GAME SELECTION PROCESS FOR MODDING PROJECTS 10 Finally, Table 2 summarizes the potential modding forms achievable by each modding technique. It is based on a review of VG architectures (Sheldon et al., 2009). Table 2: Matrix of modding forms vs. modding techniques.