Duke Nukem 3D: 20th Anniversary World Tour is a re-release of Duke Nukem 3D to commemorate the 20th anniversary of the game. Optionally the game can be played in 3D instead of 2.5D as with the original version of the game. There is also an ability to rewind the game progression instead of resorting to save and load routine. It has three episodes from the original game plus another one called Birth from the Plutonium Pak add-on. The additional expansion packs from the Megaton Edition are not included.
Entirely new content is a eight-level-long episode called Alien World Order that has maps designed by the original map-makers. Most of them are modeled in spirit of the capitals of the world which aliens decided to infest. There is a new weapon: the incinerator spits a flammable liquid. There is also a new enemy called Firefly. The new episode features a new soundtrack from the original series composer Lee Jackson, and a new voiced lines by the Duke's voice actor Jon St. John. Some levels feature in-game developer commentary.
In this edition of the game, the medkit sprites were edited so that instead of a red cross, they depict a red-and-white pill. This is likely because the rights to the red cross symbol are owned by the International Committee of the Red Cross (who have expressed concern that usage of the symbol in video games cheapens its special significance), and its usage in video games technically violates the Geneva Conventions.