- Not to be confused with its sequel Back to Saturn X: Episode 2
Back to Saturn X: Episode 1, abbreviated in-game as BTSX: Episode 1, informally known as BTSX 1, sometimes elongated to Back to Saturn X: Episode 1: Better Texturing with STARTAN-X, and possibly wrongly referred to as BTSX or Back to Saturn X is a 27 mission mod for DooM II devolped by BTSX Team and released on December 10th, 2012. Along with new levels, the mod also boasts new music tracks, textures, and sprites. The goal of the mod is to create a brand-new gameplay experience, while still retaining the gameplay-style of the original DooM II. Although not officially developed, licensed, or published by id Software, it is officially supported by them, as it was released as a free add-on for 2019 remasters of The Ultimate Doom and DooM II/The Master Levels, alongside its sequel Back to Saturn X: Episode 2, on June 26th, 2020.