"[3] Dellis was born in Wimbledon, UK, to a Belgian mother and a French father, and grew up in England, France, and the United States.

He then earned a master's degree in computer science, also from the University of Miami, and wrote his thesis on automated reasoning.

Dellis was featured in the 2012 documentary Ben Franklin Blowing Bubbles at a Sword: The Journey of a Mental Athlete.

: An Adventurous Guide to Remembering What You Don’t Want to Forget" (2020), a memory technique how-to book for kids in school.

[5] Fusion-io sponsored an ascent of Everest in 2013, following up on a 2011 attempt in which Dellis had to turn back 280 feet from the summit due to equipment failure.

Nelson was a contestant on Superhuman, the American version of The Brain, making it to the finals of his episode by memorizing bank vault codes and then having to open them from memory, while being suspended from the ceiling.

[62] Nelson has been featured in The Wall Street Journal,[63] The New Yorker,[64] Mashable,[65] CNN,[66] Yahoo!,[67] Lifehacker,[68] Vital Signs with Dr. Sanjay Gupta,[69] Today,[70] Men's Health,[71] among others.

In 2012, Nelson began production for a documentary called Memory Games with Emmy Award-winning director Janet Tobias.