FullDive (フルダイブ, furudaibu) is a technology that immerses the player's senses in a virtual reality. It serves as the technological basis for most of the stories throughout the Sword Art Online series.

The system appears realistic enough to trick the mind on a deeper level, and the player's body can react with real responses to imagined injuries, such as spasms or spikes in blood pressure. Safety protocols and sensor networks are implemented to prevent the player from overexerting themselves.

Known FullDive compatible VR consoles

• At least one arcade machine
• NerveGear
• AmuSphere
• AmuSphere 2 (provisional)
• Medicuboid
• Brain implant chip
• Soul Translator
• Neurological Link (Crossover Accel World)

2nd generation

NerveGear

Argus created the NerveGear , a 2nd generation (1st generation in the Gun Gale online FullDive gadget. It is a headset with an internal battery power source that covers the player's entire head and part of the face. It has indicators for power, connection, and an indicator marked "BLK" (which supposedly indicates data blocks being transferred). Once worn, it recognizes the player by saying "Link Start" and connects to the player's senses by connecting to the brain-body signaling system and becoming the endpoint for control signals, while also providing the virtual reality feedback. It uses microwaves to control nerves.

When the NerveGear was released, it was ahead of its time, and game makers weren't fully utilizing it at first, developing puzzle or educational games, walking simulators, and more. Sword Art Online was a much-anticipated leap forward. It was eventually used to trap all ten thousand online players during Sword Art Online's official launch of FullDive technology in November 2022. This is also the first FullDive technology to be mass-produced.

AmuSphere

The AmuSphere (TV series) amyusufia ), which is short for "amusement sphere," is a 2nd generation FullDive system that was co-developed by Yuuki Shōzō's company RCT Progress Inc. FullDive Division headed by Sugou Nobuyuki. The system has been modified to emphasize player safety. Indeed, the AmuSphere's microwave emitter now has a strict power limit, while various sensors have been implemented to constantly monitor blood pressure and brainwaves and cause a safety disconnect function in case the player's stress level puts them in danger ( Gun Gale Online novels imply that this was also in the NerveGear, and it was possible to opt out). Additionally, the AmuSphere allows for some of the real-world sensory experience, so it would be possible, for example, to wake up a player, and some players would play in a dedicated isolated room for a purer experience.

3rd generation

Medicuboid

The Medicuboid (TV Series) Medicine ) is a 3rd generation FullDive system whose primary purpose is health. It was designed by Kōjiro Rinko, who improved the original machine Kayaba used to copy his online memory. The Medicuboid is more than just a headset that replaces the sensory synapses in the user's brain and also connects to their spinal cord. Its specifications are also far superior to those of a game console, increasing the effective connection bandwidth of the computer hardware and, ultimately, the speed of the player's reflex chain and reaction time.

The Medicuboid's primary use is not for entertainment, but rather to allow people with sensory impairments to connect with the real world, as well as to act as an anesthetic, and more. This is achieved by connecting their senses to external sensors, such as cameras and microphones.

4th generation

Soul Translator

The Soul Translator (ソウル・トランスレーターsourû toransurētā ), or STL, is a 4th generation FullDive system invented by Higa Takeru in Rat. It is the first system that officially bypasses circumvention means like interacting with a player's senses, and instead connects to the user's Fluctlight (soul or consciousness) directly. This is based on the assumption that the human self is built on a mixture of biological influences and electrical and quantum phenomena as means of computation.

Naturally, for a system of this level of connection, the STL system has some innovative and revolutionary features. One of its core functions, called Fluctlight Acceleration (FLA), is the control of the Thought Clock Control Signal , which is something that has not yet been well studied but is analogous to the touch pulse generator in a computer's CPU. This allows the user's synaptic chains to be overclocked in the same way, which usually reduces the time that passes in virtual reality by up to five thousand times compared to the real world. The STL also places the world's scenes directly into the player's memory, in a dream-like manner, causing the mind to cease to make a critical distinction between the rendered world and the real world.

The STL was targeted by the Alicization project to recreate a human's Fluctlight for use in highly adaptive artificial intelligence.

Brain implant chip

A 4th generation FullDive system that was implemented in Accel World and is mentioned in SAO as being a research-stage technology developed at Santa Clara University. According to Kazuto, the STL equipment was far too heavy for commercial use, and thus brain implants represented the future.

FullDive Non-Compliance

Because all humans are biologically unique and interacting with FullDive equipment requires precision, immersion systems must be meticulously calibrated and customized during an initial connection test routine that takes some time. However, some people's physical appearance exceeds the equipment's margin of error, and the test may result in a "FullDive Non-conforming" (フルダイブ不適合) result. In most of these cases, the game would still be playable at the cost of a malfunction in one of the senses or a slowdown in the experience; however, some people are completely incompatible with commercial-grade FullDive systems.

Anecdotes

• The NerveGear is mentioned in the Accel World light novel series without a given title. Accel World TV anime confirms the title in episode 22.
• In SAO web novel, A NERve Direct Linkage Environment System or NERDLES (ニードルス, Nīdorusu) is used.
• The Augma, an Augmented Reality console that shouldn't have FullDive capability, secretly ends up having it.

References

• Full Dive - Fan Wiki