Below are tips that I've learned by building a practice project, working an internship at a VR studio, and going to conventions.
5. Frame Rate
Games run around 30 - 60 FPS. However, the camera in VR is
essentially two cameras set slightly apart, both rendering the scene at the
same time, so a normal scene that would run at 60 FPS, now needs about twice
the processing power. Most studies show that 60 FPS is the bare minimum to
prevent motion sickness. In fact, Sony Playstation VR at GDC 2016 even told
developers flat out they can never EVER drop below 60 FPS or they will not
publish. The golden number that everyone seems to agree on is 90 FPS for HMD’s
like the HTC Vive, and 60 FPS for phone-based headsets, and if kept constant,
you can avoid motion sickness, lag, and overall frustration from players.
In Unity, you can very easily get a rough estimate of your
FPS by clicking on stats in the game scene, or going to Window à Profiler (Ctrl + 7),
then turn vsync off by going to Edit à
Project Settings à
Quality. (Turning VSync off will give you a more accurate view of usage since
it won’t try to sync up with your refresh rate, but remember to turn it back on
before building). The profiler is especially helpful because it shows a breakdown of what is taking up the most space.
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| Clicking on stats in the game window can give a quick idea of FPS |
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| Turn vsync on and off by going to Edit -> Project Settings -> Quality, then bottom of the inspector |
Below you can see examples of what it is with vsync on and vsync off:
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vsync on |
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| vsync off |
4. Console
This may sound obvious, but when I started this project, I
naively thought I could adjust a few things here and there and make the game
compatible with any VR headset. Then when I was finally able to test it, I
realized each have their unique controls and feel. For example, in the Gear VR,
this laser looks like it’s coming out of my crotch, but in Oculus,
it looked higher. Also, because I click to shoot, I turned off the mouse
look for Oculus, but then swiveled around with my head attached to the computer
and right arm attached to a mouse. You can see the embarrassing results in the
video below. It felt great in Gear VR because I was less tethered and could
easily use the action button on the side to shoot. I know it sounds obvious
NOW, but hindsight is 20/20. Really what I envisioned for this game is being
played on is an HTC Vive, 2PV, but alas I was a student and only able to get
what I could borrow.
3. Art
Keep your frame rate high by OPTIMIZING everything. Don’t use
complicated lighting, or materials that bounce light, like a ton of specular
highlight, glowing, or metallic stuff. Not saying you can’t use ANY, but do use
sparingly. Also eliminate real time shadows and bake your lights wherever
possible. Same with textures, and avoid using too many different ones. I spent
a ton of time modeling a cute little robot to dance around in space, but ended
up trashing it because of how many polygons it had (not to mention a shiny
metallic material). It went up by 500+ FPS when removed, not that it mattered much since it was above 100 FPS to begin with. I didn’t have to do
too much optimizing, but you can click here for Unity’s list of optimization
techniques.
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| DJ BroBot |
2. Motion Sickness
I separated this from frame rate because frame rate isn’t
the only thing that causes nausea. The biggest issue stems from these little
things called otoliths in our the inner ear that help us balance. Here’s how
I’d describe this amazing evolutionary feat. Imagine three hula-hoops placed on
a separate X Y Z axis. Each hula-hoop is filled with sand, and at one point is
a sensor that detects what direction the sand passed and how fast they
moved, which provides information to your brain about where you are in
relation to gravity and acceleration. Also imagine that this system has been
co-evolving with your eyes for billions of years, and now all of a sudden, you
have this device that shows you’re moving really fast, but your inner ear
thinks you’re stationary. No matter WHAT you do, this
problem will always be there for some people. There are a ton of tricks, but
you’ll just have to accept that nothing will help everyone. Don’t compromise certain
things just for those few who will never get past that feeling. Here’s a list
of ways to combat motion sickness:
A) Sit
still. Don’t even give the option to walk. Games where you sit, look around, or
interact with objects around you work well. Two really cool ways I’ve seen of
handling this I saw at Indiecade last year – Floor plan, a puzzle game that
takes place in an elevator, and Kismet, a fortune teller who also plays an
interesting board game. The best way I’ve seen it done is Job Simulator, a
sandboxy game where you simulate working a boring mundane job. That's why in my project, you stand in the middle and shoot.
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| Job Simulator |
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| Floor Plan |
B) Have
something in the field of view that doesn’t move to ground the player. Think of
a car, you see everything fly by you, but you don’t feel like you’re moving.
This frame of reference is easy to handle for your brain. I’ve only ever seen
this NOT done well once. Narcosis, although a great idea for a game, missed the
most magical and addicting part of VR, looking around in 360. You can’t turn
your head around because you were in a deep-sea dive suit with a helmet that
doesn’t move. It felt limiting and claustrophobic. Below is an
example of a ship I modeled for an underwater exploration type game. As you can
see, there’s many windows so the player can look in all 360 while still seeing
parts of the ship in their peripheral.
C) Move at
a constant and slow rate, don’t accelerate suddenly. If the player has to move,
make sure they are in control of it. ElemenTerra is a great example; you float
around terraforming this planet in a very Minecraft-like way. The movement is
slow and never jerky. Another one I tried, VirZoom, has a flying Pegasus game
where you eat apples in the sky; the controller is actually a stationary bike. The movement was steady, but you also had a Pegasus head and wings to make you feel grounded. The only time
I’ve seen this not done well was Fathoms Below, an undersea mermaid puzzle game
for GearVR. In order to move forward, you had to bob your head up and down as
if you were a swimming mermaid. However, I moved so slowly that I felt the need to bob my head fast and it felt like a chore, not to mention the
whiplash.
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| Fathom's Below |
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| ElemenTerra |
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| Virzoom - Flying Pegasus Demo |
D) If you
need to move long distances, tunnel the player’s vision. I first saw examples
of this a few years back playing Mare: I didn’t play it long enough to get the
story, but it’s a kind of puzzle adventure game where you’re a flying crow. You
look at something in the distance and get to it by having everything wormhole
around you. The one time I didn’t think this technique worked well was when I
played the new Psychonauts demo, Rhombus of the Ruin. The ship you’re on is so
small I felt the mechanic was unnecessary. It would’ve worked just as well
pointing and clicking from one spot. Before you go saying, “Well Raz has
special powers that allow him to do that anyway”. I say,
yeah, and one of them is telekinesis, so what’s the point of jumping into
another person’s body that’s less than three feet away just to move a magazine? The best example of all time, however, is Land's End, the newest VR experience by the studio that brought us Monument Valley. It doesn't tunnel your vision, but it gives you a target to move toward so you focus on a particular spot.
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| Psychonauts - Rhombus of Ruin |
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| Land's End |
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| Mare |
1. Gameplay
Although this list may make you nervous, all these rules and
limitations can be intimidating, but some of the best art comes from adversity
and working around limitations. If you’re a gamer that likes the AAA art, as
realistic as possible, dipping ever so slightly into that uncanny valley, then
you’re definitely not happy about #3. If you’re a gamer that loves crazy cool
game mechanics inside open worlds and lots of fast paced fighting or
exploration, you’re definitely not happy about #2. But I’m here to tell you,
some of the most creative games I’ve ever encountered were made in VR, and
that’s why I’m so excited about it. Focus on the gameplay - on being
original – think of your restraints more as guidelines.
