3D Realms is a publisher based in Aalborg, Denmark. Scott Miller founded the company in his parents' home in Garland, Texas, United States, in 1987 as Apogee Software Productions, to release his game Kingdom of Kroz.
In the 1980s and 1990s, the company popularised the shareware distribution model for video games and created successful game franchises, such as Duke Nukem.
Apogee adopted the trading name 3D Realms in 1996; the "Apogee Software" name and logo were sold to Terry Nagy in 2008, using which he established Apogee Software, LLC.
Following two extensively delayed games, Prey and Duke Nukem Forever, 3D Realms laid off significant portions of its staff and underwent a corporate restructure, retaining only production and publishing roles thereafter.
In March 2014, the company was acquired by SDN Invest, a Danish holding company and part-owner of Interceptor Entertainment, and relocated to Denmark by December 2014. Miller remains an adviser for the company.