inVadeRs - VR Title
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Project Overview
Developers were given the task to produce a video game which would work in VR, primarily on the VIVE system, in which the game would last around five minutes. The core goal being that the game would be presented at a games development show later in the year and must showcase their work to each player and spectator efficiently, whilst creating a spectacle to watch.
The entire game was produced by myself, working on the blueprints, procedural music, art, models, sound FX and particle systems. Some sound FX and particles were sourced and edited to fit the project.
Early Concept
The brief was very ambiguous in what the developers could achieve, however, due to the lack of knowledge in the area of VR development the team decided to keep the scope of the project and key mechanics to be relatively simple or areas they had tackled in the past.
Style of Game
I decided upon remaking classic video games in the modern VR setting, such as Pac-man (Namco, 1980), Donkey Kong (Ikegami Tsushinki, 1981) and Space Invaders (Taito, 1978) respectively.
Firstly, Pac-man is a game primarily about directing an entity around a plane of existence in which they collect artefacts and avoid pursuers. I however, felt this would not translate efficiently into VR when taking into consideration movement options in VR, especially with one member of the team susceptible to VR motion sickness.
Secondly, Donkey Kong on the other hand is a game built on the premise that the player must make it past obstacles in order to meet a goal location whilst an antagonist is trying to prevent their progress. This whilst another interesting concept to tackle did not immediately feel it would translate to VR well, especially in terms of core gameplay, in line with the fact the game must be a spectacle both to the player and spectators.
Finally, Space Invaders is about destroying entities attacking the players home before they reach and destroy aforementioned home. Immediately there was a correlation in achievability for VR here, as the team could effectively have a player defending, standing in place, against multiple waves of attackers.
An initial concept allowed the me to decide upon having a player survive alien waves attacking their city, trying to destroy their lives, or buildings (Fig.1 below), and bring this into the modern world of computer games by having procedural enemies. To further emulate the feeling of Space Invaders and the original view of an ‘invasion’ or ‘army’ coming towards the players buildings the enemies in the game would lineup at a rally point (Fig.2 below) before heading to buildings.
Fig 1 - Space Invaders by Taito Fig 2 - inVadeRs by James Tyler
The name of the project was to be inVadeRs (Tyler, 2019), both utilizing a direct correlation to Space Invaders in name and showing VR as the highlighted capital letters, giving a subtle emphasis on the fact it is a VR title.
Aesthetic Theme
Next, looking at the aesthetic theme of the game, along with the goal of being a spectacle to watch, I decided upon a synthwave-retro aesthetic. These bright neon colours could draw people’s gazes faster than dull more receding colours, as seen in studies of children which prefer bright colours over others, with the common trope that bright colours are more stimulating and interesting (Pancare, 2018).
Figure 4 - Colour Harmony for inVadeRs
Delving deeper into colour allowed me to decide to cater towards colour-blind players, by having a toggle-able mode in the game. This was due to the revelation that swapping the colour Violet for White for a colour blind individual would mean they would not have as many adversities to playing the game as other games may yield due to confusion between colours.
Other games such as FTL (Subset Games, 2012) has a colorblind mode which along with changing the colour scheme also adds patterns, which helps further segregate colours on screen for those suffering from the ailment. Cameron Gidari states that players that are affected by colorblind ailments are around 10% of male players and around 1% for female (Gidari, 2014), however if you consider if a game has a player base of around 1 million players then that is around 100,000 players potentially suffering when playing the video game, if measures are not in place. Therefore the changes made albeit small in swapping purple and pink to white could lead to substantial amounts of more satisfied customers in turn increasing potential sales and more positive reviews.
Figure 5 - Normal Mode Figure 6 - Colour Blind Mode
Five Minutes of Gameplay
The design brief stipulations stated that the game must be playable for around five minutes of content. This is unusual amongst most games produced as most game developers want the player to be playing for vast quantities of time, gradually build up their mechanics or systems within the time played, usually in line with a predetermined campaign or multiplayer structure of progression. However, to adhere to this stipulation and also have the player, if they so wish, to continue playing and want to do so I decided to add certain features to this goal, such as leaderboards, randomized enemies, multiple difficulties and procedural music.
Leaderboards
Leaderboards are a staple in video games, especially ones that deal in hi-scores, since the time of early arcades, with Space Invaders (Taito, 1978) being heralded as the first game to use them. They allow people to compete with one another as well as show their ‘skill’ within the video game to other spectators and have a record of their achievements.
Keeping in tandem with the fact the game would be primarily based upon Space Invaders, I decided to have the leaderboard's show a three letter name and then the hi-score attained of the player as well as the leaderboard's themselves showing only the top ten players in each difficulty. The three letter input gives an immediate retro-vibe when inputting the player name on the virtual keyboard on level completion, but I also had to implement a name check feature to get rid of any names that could be considered offensive, as many arcades in the 80s and 90s did have people inputting certain derogatory terms (Game Sparks, 2017). Looking deeper into leaderboards I found that companies such as Microsoft have the requirement that any game released on Xbox live must have some sort of leaderboard implementation (Microsoft, 2018).
Figure 8 - Easy wave example
Looking at the above picture (fig.8) the player could shoot the leftmost enemy and then work their way to the right with no real reason not to do so. Therefore a second enemy was devised, which forced the player to have a higher percentage chance of having to utilize both their weapons on one enemy.
Figure 9 - Advanced wave example
This new enemy, with a model design based on ghosts from Pac-man (Namco, 1980), had a 100% chance of spawning with a shield compared to the purple invaders 50% on medium, but also its body was a color also which meant it required shooting with the correlating weapon as well. In the above picture (Fig.9) the far left enemy ghost would require two shots from the blue weapon, however, the far right ghost would require firstly a shot from orange and then the blue weapon.
New observations during testing, which was staged in weeks 4 to 6 of development, showed players now instead of systematically shooting from one side of the wave to the other started to pick targets and would reassess what to shoot next every couple of shots and most predominantly during the downtime of a reload. This new methodology of play also helped the game reach another target goal of being a spectacle to watch, due to the player often swapping stances during game play and sometimes even crossing their weapons to hit different targets.
Multiple Difficulties
Another aspect that was added to the game to extend the gameplay as well as cater to a larger audience was multiple difficulties. Apprentice was devised to people inexperienced with VR could pick up and play the game, whilst having a platform to gradually get better and eventually upgrade to Sentinel. Sentinel on the other hand was the middle difficulty which increased both the speed of the enemies spawning system and their approach to both the rally and buildings, thus giving the player less time to destroy them. The final difficulty of master would further these speed increases and working in tandem with the randomization of enemies also produce harder enemies to destroy with a greater chance for both shields and ghost type enemies on this difficulty setting.
Figure 10 - Main Menu Difficulties
This three tier structure for difficulty is common in most video games. Offering three distinct gameplay situations for the player to experience. This gives benefits over having just a single difficulty due to catering to more player skills, having more choice for the player to impact their gameplay experience and due to the fact that each difficulty has its own leaderboard, more chances to reach a leaderboard position effectively raising from 10 slots to 30 slots.
Furthermore, to help players both unfamiliar with VR and for learning the key elements of inVadeRs an in-depth tutorial was added in the main menu, allowing the players to learn about shooting enemies, shield systems, multipliers and power ups.
Retro Elements and Easter Eggs
Taking into consideration the game was based on Space Invaders and other 80s arcade games, the developers decided to implement other retro aspects and Easter eggs. The first of which to be implemented was ‘Pman’, which once shot would give a multiplier bonus of x10 as well as play the retro noises on spawn and destroy from Pac-man (Namco, 1980). This aspect, whilst random in the game in timing, was built to appear at least twice during each game, making sure that all players would at least experience the event in their five minutes of gameplay.
Furthermore, during gameplay, multiplier increases are often announced via sounds directly from Unreal Tournament (Epic Games, 2004), with Mortal Kombat X (NetherRealm Studios, 2015) announcements being used for ‘OHK’ (One-hit-kill) powerups, victory and defeat states. Mortal Kombat X was used due to the sound quality, but the phrases such as ‘finish him’ and ‘flawless victory’ have largely remained the same since the first games in their respective series.
Figure 11 - 'Pman' Appearance
Music Soundtrack
The music produced for the game was built in various loops, broken down from tracks produced by myself specially for the game. This allows the music to be procedural for Track 1 and 2 in the game, whilst I added a bonus track from a great rock band, which fits the game, to show what the music could be like if longer than a few days had been spent on music.
VR Considerations
Motion Sickness
Motion sickness in VR titles is a prominent worry for most developers willing to produce a game for that medium as it can put players off both purchasing and playing the game. However, there is no definitive method to completely eliminating this aspect of VR play (Kershaw, 2017), as each player can have different thresholds and game aspects they can complete before feeling the effects (Qualls, 2019).
Some of the ways I lowered the probability of motion sickness were by having the player standing predominantly in one spot, eliminating common motion sickness causes, less camera attached feedback and effects, short levels, ability to pause the game and finally frames per second.
Player Movement
Firstly looking at the players movement, having the player standing relatively in place atop a skyscraper was the core of the experience, in comparison to having the player move around the environment or constantly turning over 90 degrees in angle. This meant the player did not need movement mechanics, such as teleportation or smooth movement which is common in other VR titles like Skyrim VR (Bethesda Game Studios, 2017) and Doom VFR (id Software, 2017), but can cause motion sickness but add immersion (Jagneux, 2017), with personal experience from myself.
Furthermore, the game can be played either standing or in a seating position, which allows players to choose their comfort of play as well as giving the affordance of seating being less susceptible to motion sickness than standing whilst playing VR titles (Merhi, Faugloire, & Flanagan, 2007).
Vection
Another key consideration was vection (Hettinger & Riccio, 1992), which is when a person feels the sensation of movement through visual stimulation (Mason, 2015), this is lowered by having focal points in front of the player at all times, with the base of the skyscraper in the main menu acting as this and the horizon in the main game levels. This was key in lowering motion sickness as vection can come to the fore when enemies were moving towards the player or the items on the main menu were scaling in and out.
HUD and UI
Next, the team tackles not having heads up display directly on the camera as this can cause motion sickness with the staple for VR games being to have world space user interface (Borrell, 2015). This meant that all visual feedback for the mechanics in the game had to be actual actors in the world, such as the scoreboards and multiplier bonus, which for narrative reasoning were made to look like billboards atop of buildings, seen in top left and bottom right of the below screenshot (fig.12).
Figure 12 - Scoreboards and multiplier example
Breaks in Play
A key way to avoid motion sickness is short bursts of gameplay, such as playing a game for 20 minutes and then taking a break, the stipulation of having five minute gameplay segments and levels helped reach this goal with minimal work on the development team’s side. Another way to help this was the introduction of the ability to pause the game, this meant that players could leave the game and come back once settled.
Frame Rate
Finally, frames per second or FPS is a key consideration when it comes to VR games development, this aspect even having publishers and platform holders such as Sony stating that any game released on PSVR must be higher than a minimum of 60FPS or they will not certify the game to be on their platform (Hall, 2016). At lower than 60FPS a video game in VR will cause motion sickness due to the jumping and shaking of the camera. This was tackled by trying to optimize the game for VR as best as possible.
VR Optimization
Throughout the development of inVadeRs, I always tried to limit as much as possible the use of any advanced functionality in the engine, whilst keeping to common tropes for VR development to keep the frame rate as high as possible. Some of these included using low-level bloom for the emissive neon colours in the game, reducing particle effects and object pooling.
Minimal Advance Engine Features
Firstly, I had no experience with VR development, thus had to learn alongside development what was possible and what was not in this medium of game design. One aspect that kept coming to the fore was things that could not be done in VR, such as dynamic lighting and some special effects.
Dynamic lighting was not so much an issue for me due to the fact that static lighting could be used and shadows turned off for everything in the game with little or no effect upon the visuals and believability of the game due to its stylized approach.
However on the other hand, the loss of the effectiveness of bloom proved a challenge at first, due to the games reliance upon emissive colorization for both the weapons and targets. These colours often appeared watered down and, not representing the artistic vision entailed for inVadeRs, a compromise had to be made in order to try to make them appear as designed. At bloom stage one, the frames for the project was 78, with stage 2 being 68 but representing the core goals more, therefore a stage three iteration was made with bloom values being in-between and still giving a frame rate of over 75.
Figure 13 - Bloom non-VR version. Figure 14 - Bloom final VR version.
Reduction of Effects
As I had already lowered the effects of bloom and other advanced features, I looked at further optimization by reducing effects already in the playable version of inVadeRs, such as particle effects and sounds.
Starting with particle effects, each system was lowered in intensity, with some mostly having features to be a spectacle for the player to see, such as enemies exploding and the buildings losses. I started to delete and remove effects from these until they could not delete any more aspects without losing the ‘spectacle’ of each event. Furthermore, some events in the game which had particle systems assigned were removed entirely to increase performance.
Object Pooling
Object pooling came into play due to a noticeable drop in frames each enemy wave, this also correlated to the garbage collection for inVadeRs, with the GC being moved to a quicker interval. Utilizing object pooling reduced the frame drop from 75 to 21 (under extreme conditions) to around 56. However, it is worth noting that playable EXE versions did not suffer this immense drop and this was only prominent in PIE (play in editor) on Unreal Engine 4 (Epic Games, 2018).
Reflection on Project
In conclusion to tackling VR development, there are many different key considerations. Whilst a development team can decide what style of video game they want to produce and the aesthetics there are other considerations such as motion sickness and optimization that must come to the fore in any features to be implemented into a VR game.
The game inVadeRs, aims to tackle these in every aspect, from core mechanics to visuals as well as catering for players that are often overlooked in video games, such as colorblind and deaf players.
Furthermore, constant testing was found to be the core ingredient in fixing user experience issues such as needing a mini-tutorial on the main menu and other aspects of the game that needed tweaking for the player to understand and get the intended developer experience for the game.
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Figure 7 - inVadeRs virtual keyboard
To have the player input their name into the leaderboards it was decided upon to have a virtual keyboard (Fig.7 above) to appear once a level had ended. However, instead of pressing buttons the team felt the player could shoot ‘windows’ on a skyscraper, this meant that no additional mechanics had to be produced just to input the player name, utilizing the standard gun mechanics already produced.
Randomized Enemies
To further enhance the longevity of inVadeRs, I decided to implement enemies that would react both to each other and the games demands but also be randomized in a way that felt fair but challenging. This initial randomization came from shields being added, randomly, to enemies on their creation, either an orange or blue shield correlating directly to each gun the player wields. The correlation between shield and the weapon is not just for aesthetics however, being a core gameplay element of shooting the enemies with the correlating weapon colour to take down the shields.
However, due to initial testing in week 3, both observational and direct feedback, the players required more types of enemies to destroy as they would just systematically destroy the waves of enemies with no real reason to focus on one enemy over another.
Figure 3 - Example of Synthwave art.
Furthermore, the colours of ‘Yellow-Orange’, Violet and Blue are dominant throughout ‘Synthwave’ art (Fig.3 above), this gives the game an instant split-complementary colour harmony system.