Accel Assault 2038 is a game of similar type as Brain Burst 2039 and Cosmos Corrupt 2040. Its existence is first mentioned by Green Grandee in Volume 9, and is further elaborated on in Volume 16 by White Cosmos who states the game was discontinued for endless conflict. In addition, while not canon, the first bonus episode, Reverberation, packaged with the first video game, Accel World: Awakening of Silver Wings, features the game's final death.
Accel Assault 2038 was a VRMMO that was similar to Brain Burst (BB) 2039, and created by the same developer. Green Grandee refers to it as Trial No. 1, with BB 2039 as Trial No. 2 and Cosmos Corrupt (CC) 2040 as Trial No. 3. However, like CC 2040, it is now deserted.
It was inhabited by players called Assault Linkers, and appeared to use the same Acceleration commands and methods as BB 2039. However, unlike Brain Burst, every player in Accel Assault was pitted against one another in a free-for-all. Eventually, all the players were defeated, and the world was abandoned.
Like Brain Burst, the virtual world was mainly constructed using the Social Camera Network. However, also like the other two "trials", the Imperial Palace was devoid of any cameras. This leads to Archangel Metatron's speculation that the Imperial Palace itself is the true goal of all three games, as well as that of the developer.
- In the OVA episode packaged with preorders of the first Accel World game, Accel World: Awakening of Silver Wings, Haruyuki, Kuroyukihime, Chiyuri, and Takumu are all brought into Accel Assault in order to defeat the final Assault Linker still there. However, the environment doesn't appear to be taken from Tokyo -- this is because that was a plot point only brought up in Book 16, which hadn't been translated yet.
- Accel World 9: Prayer of Seven Thousand Years ("Correct. 《Accel Assault 2038》, which came before, and 《Cosmos Corrupt 2040》, which came after, have been deserted for a long while. It is likely that some cause that Number 1 and Number 3 lacked exists here in Number 2. Until that cause materializes, I cannot allow this world to be closed off." -Green Grandee)
- Accel World 16: Princess Snow White's Slumber