I am standing on the rooftop of a skyscraper in an unfamiliar metropolis. The ground is a long, long way down. Pigeons fly away as I step closer to them.
Click. A harness is strapped on. My heart is in my throat, I can hear the wind in my ears.
It is too much.
Vertigo hits and I ask, shout, for the simulation to stop. In a panic, I've forgotten that I can pull off the virtual reality headset that has put me in this thrill-seekers' space.
Back at the VRCade installation in Vodaworld in Midrand, Johannesburg, it takes a minute to re-orient to actual reality.
The brainchild of Zach Joubert, a lawyer turned tech-head, VRCades (one in Joburg and another at the Waterfront in Cape Town) offer a taste of the technology that is soon going to take over our world.
No exaggeration. Walk on the moon, dive the Galapagos Islands, navigate the seven wonders if you will.
While Joubert's arcades are primarily about gaming (the zombie apocalypse is brilliant), and gaming is the space where VR is developing rapidly, it is coming to every aspect of life, from space travel to medical science to shopping.
Expect it in education - think field trips from a Limpopo classroom to Christ the Redeemer's statue in Rio or King Tut's tomb in Egypt. Mining, engineering, architecture and house buying are quickly being revolutionised - see how scaffolding will hold up in a mine shaft, walk through the future building in your head, rearrange the furniture or change the paint colours. From London, survey the property on sale in Camps Bay.
The tech is a teenager, developing rapidly but difficult to get hold of. Headsets like the HTC Vive and Oculus Rift came out commercially last year. Content producers are making magic with a laptop and a cellphone, cheaply and abundantly.
Joubert says: "There were a few false starts to VR since around 2014, but with the convergence of phones and HD screens, faster computers, it is here. It is immersive, brilliant technology. You truly feel like you are in another environment."
An underwater experience puts me in a whale graveyard; next I am painting in the desert with a 3D light brush. It is not accessible for home use yet, but at Joubert's arcades you can buy an hour for R200.
"It was a no-brainer to bring it to South Africa, but in rental model because the hardware is expensive. It will become more accessible," says Joubert.
"The lower-tech PlayStation VR is coming in February, the Samsung Gear is here. For now, I wanted to create a video game arcade because I loved that social aspect of gaming. No more playing video game consoles alone in the living room."
South African brands are playing with the technology, especially in the motor industry. You can create and drive your customised car without entering a showroom
The commercial world is alive to the potential in marketing, using both VR and AR - augmented reality, in which tech "enriches" the existing real world.
"Brands are playing with it in South Africa, motoring especially," says Joubert. Create and drive your customised car without entering a showroom.
"Internationally, the online store Alibaba released a VR shopping experience - you can go into a store, pick up what you want, look at it and buy it. Skip the mall, traffic and parking," he says.'
It is not only for technology junkies. Some games take you to a forest or mountain peak where you can create artworks. Museums have been among the first to embrace VR.
The Salvador Dalí Museum in St Petersburg, Florida, puts you inside a painting created by the Spanish surrealist in 1935,Archaeological Reminiscence of Millet's "Angelus".
You can venture into the painting's towers, peer from them to distant lands and discover surprises around every corner, the museum promises.
Madame Tussauds wax museums recently piloted a "ghost busters" experience in which visitors explore a physical environment, augmented with VR ghosts.
You could sit next to Da Vinci while he paints the Sistine Chapel.
'Frightening and infinitely exciting'
Joubert says: "[Virtual reality] is a little daunting, a paradigm shift with the way people interact with machines. Like any other tech, you can't spend all day losing contact with other people. We have to use it with caution and it will be powerful."
Marco Rosa, MD of Formula D interactive, a VR content developer, finds it frightening and infinitely exciting.
"The reality is that it is here. The applications in entertainment are easy to understand, in gaming. In a movie, how will we be involved in the plot, get involved in the role?
"Some of it is strange. Sex ... you can imagine. Sport, to be able to be at any stadium in the world. For travel, spend a couple of hours in the Maldives, or what about Fukushima? The point is that it enhances our reality. If you want to gain empathy for refugees in a camp in Jordan, you can be there with them."
Rosa says the most interesting application is education. "Can you imagine studying ancient Egypt by visiting the tombs? The memory retention because they can do it over and over, whenever they want will be incomparable.
"Game-like experiences for medical students without the threat of hurting someone. Learning history? Watch the meeting between Churchill, Roosevelt and Stalin that ended World War 2," says Rosa.
"Nothing beats first-hand experience but it has major capacity, cost and accessibility constraints that VR easily overcomes. VR is much more scalable, accessible and cost-effective already. And that is all going to increase exponentially in the very near future."
Exciting job-creation potential
Rosa says that the best way to ensure VR is not abused and remains "safe and beneficial" is to get the best designers involved. South African developers, he says, "can absolutely compete with their international counterparts, so there are huge amounts of opportunity all round within South Africa."
Like the students of VR development lecturer Lars Espeter, who are being snapped up the moment they qualify from Friends of Design Digital Arts Academy in Cape Town.
Espeter says the field has exciting job-creation potential.
"One of my alumni is using his VR skills for an engineering company. Another is in architecture, creating 3D houses with clients. The game tech can show you photorealistically, and then make it interactive.
"The challenge for an academic in this field is that technology evolves so fast that new skills and up-skilling are continuous. Interactive entertainment has been predicted by analysts to be the third most important future market, right after biotechnology and robotics."
For now, look out for 360° video, which is the most basic form of VR.
"Lower-tech VR systems like the Samsung Gear VR and Google Cardboard use smartphones in the mainstream," says Espeter.
"Those systems are really capable, everyone has them and they are easy to use. Right now, 360 video is the big thing because it does not need game technology development skills, but that is a very limiting approach. We will see great VR interactive projects emerging throughout next year - made in South Africa."
Espeter says South African VR expertise is the equal of that in Europe and Asia. Gaming company Sea Monster, for example, won international awards for the AR SuperAnimals app piloted by Pick n Pay.
MD Glenn Gillis says: "It broke every box-office record in the app stores."
The concept was simple. Children collected cards with pictures of animals on them, which could be scanned into an app. The animals "came alive" in 3D, with sound and fast facts displayed.
This year, Sea Monster's focus in on developing educational AR apps.
Gillis predicts VR will develop like filmmaking. He cautions about the possibility of nausea when using a VR headset.
"When a camera moves in film, it creates drama and tone, but if you are out of sync with the user in VR, you get nauseous immediately. The inner ear dictates that if the peripheral vision moves suddenly, you can throw up. We will be starting to figure out how it works best in the next three to five years," he says.
Gillis is using VR in soft skills training. "In the health space, sexual education, we are creating something where a teenage girl can choose her own adventure. The decisions you make now have implications for the future; imagine if you could put yourself into a scenario of being a grown woman, based on decisions you make as a teenager?
"We are desperate for new ways of learning, and classroom experience can't be rivalled. But Sea Monster is super keen to pursue it by leapfrogging into the future.
"We see education as being in a crisis, and VR has the power to provide a great educational tool. A teacher who can keep you excited, engaged and combat distances in Africa."
VR has the power to provide a great educational tool. A teacher who can keep you excited, engaged and combat distances in Africa
Shane Marks, MD of RenderHeads SA, which develops interactive software, says social experiences will change. "I find this to be an exciting area to explore. For example, long-term hospital patients being able to go on a trip to the beach in a virtual environment."
Rosa says the hardware challenges will soon be overcome. "At the China Hi-Tech Fair in Shenzhen, I was astounded at how much hardware is developing from smaller brands.
The emergence of many more competitors will give us even faster rates of technology development and innovation, so I expect to see those entering the consumer space more prolifically in 2017. I also expect to see a groundswell of content hitting the market.
"Everybody wants to be first to market with the latest and greatest apps. A lot of people missed the boat with the emergence of smartphone apps, so nobody wants to let that happen again," says Rosa.
The race is on, and it is out of this world.