The ride opened as X:\ No Way Out on March 23, 1996 as Thorpe Park's first non-powered roller coaster. It was marketed as the "world's first backwards roller coaster in the dark", as well as being originally themed to the concept of being trapped inside a computer virus. This theme lasted up until March 2013 when the ride underwent various changes. The roller coaster originally travelled the length of its ride circuit backwards, but this was altered in March 2013 along with the shortening of its name, simply to 'X'. New trains were also purchased from Vekoma, which run forwards instead of backwards. The addition of lighting and lasers from 2013 onwards removes the pitch black darkness that riders originally rode in.
X originally had a much lengthier queue line, but this was modified and shortened to accommodate for the "Hellgate" Fright Night maze, then "The Passing" maze, and most recently "The Cabin in the Woods" maze. This original queue line featured a room full of life-sized robot mannequins lit in UV light, and a spinning tunnel. This queue line also featured TVs showing videos about the ride, although these have all now been removed. In the exit queue line, there was a 5 ft-long model of an Eveready AA battery labelled 'Thorpe Park Power Supply'; this was removed in 2013.
The ride layout has also had many features removed since its opening. There was an on-ride photo camera which allowed riders to purchase their on-ride photo; this was removed in 2005. The lift hill of the ride had multi-coloured flashing LED light strips added in 2000; these were removed in 2013.
In 2010, Thorpe Park did trial runs of X with the safety lights turned on, to test if there would be reduced levels of motion sickness with guests.