Gray's career spanned the formative years of 3D first-person shooters, and his designs and Easter eggs remain touchstones in shooter level design.
Gray's path into games began outside the entertainment industry.
He first encountered Colossal Cave Adventure while working at a business applications company, which led him to create small games in COBOL and later study computer engineering.
Gray spent several years working in aerospace before returning to games after the emergence of Wolfenstein and DOOM.
Inspired by DOOM Editing Utility (DEU) and the burgeoning discipline of level design, he began creating and sharing custom levels on Compuserve, which caught the attention of Q Studios founder Nick Newhard.
Newhard hired Gray as a contractor to work on what would become Blood, and Gray was later brought on by Apogee to craft levels for Duke Nukem 3D.
On Duke Nukem 3D (released in 1996), Gray contributed some of the title's most memorable secrets, including the now-iconic hidden message "You're not supposed to be here.
Levelord" tucked away in the final L.A. Meltdown episode.
In 1996 he and several colleagues from Apogee formed Hipnotic Interactive (later renamed Ritual Entertainment).
At Ritual, Gray worked on the Quake mission pack Scourge of Armagon and on the 1998 shooter SiN, which has since been remastered by Nightdive and Atari.
Industry peers and former colleagues paid tribute following Apogee's announcement.
Apogee said it was deeply saddened by Gray's passing and noted his legendary contributions to Duke Nukem 3D and his lasting influence on players and developers.
Apogee highlighted Gray's inspirational legacy in level design and offered condolences.
Apogee Software co-founder Scott Miller described the loss as heartbreaking and emphasized that Gray joined the games industry in his 40s, quickly becoming a relentless worker, enjoyable teammate, and a fundamentally good person, with level work that will endure.
George Broussard called Gray a distinctive personality who was well liked and especially passionate about secret areas and player surprises.
Former 3D Realms webmaster Joe Siegler said he remained in touch with Gray long after Gray left to found Ritual and sent his thoughts to Gray's family. id Software co-founder John Romero remembered Gray as a gentle soul and an excellent level designer.
Gray's influence persists in modern discussions of level design, and his work continues to be studied by designers and enjoyed by players on contemporary platforms and digital storefronts — a testament to the staying power of classic PC-era shooters.
The game industry and gaming community mourn his loss.