The Thirteenth Floor was a comic strip originally published in the British horror comic book Scream! from March 24 1984, and also in Eagle when Scream! was absorbed into it. It was written by "Ian Holland", a combined psuedonym of Alan Grant and John Wagner, and drawn by José Ortiz.
Originally, The Thirteenth Floor had a horror theme, like other Scream! strips. It was set in a tower block called Maxwell Tower, controlled by an experimental sentient computer called Max.
Max himself narrated the strip, and as befitting a computerised custodian of hundreds of people, was quite chatty and light-hearted. However, he was also portrayed as having a programming flaw reminiscent of the HAL 9000; programmed to love and protect his tenants, he could remorselessly kill anyone who threatened or even just annoyed them. In effect Max was a psychopath with no empathy towards anyone who was not a tenant.
Maxwell Towers had been built without have a thirteenth floor (going straight from 12 to 14) for reasons of superstition; however due to a faulty I.F. (Integrated Functions) module, Max had the ability to create his own 13th floor, accessible from the building's lifts, which could contain anything he desired. Whilst he could produce any range of idyllic, surreal or mundane environments, Max seemed to have a personal taste for the horrific. in this sense The Thirteenth Floor seemed to be inspired by the Eagle strip The House of Daemon.
Max used the 13th floor to punish and torture anybody he felt deserved such treatment - often creating such fear and distress that they suffered a fatal heart attack or were driven insane. Typically, Max would notice a burglar, vandal or con-man through one of the many view screens, who would be lured into the lift, and taken to the 13th floor. Often their experience would contain subtle irony, for example a con-man claiming to be a pest controller would be chased by giant rats, or incompetent repairmen would be stuck in a burning facsimile of Maxwell Towers, in which all the doors and windows were jammed.
The 13th floor originally appeared to be a virtual reality, similar to the Holodeck concept in Star Trek which it preceded - for example, when a victim shot zombies with his gun, the lift's walls became riddled with bullet holes. However, later in the story the 13th floor was portrayed as somehow existing within Max himself - the lifts were empty when people were within it, and if Max was switched off, these people were 'lost'.
As the story progressed, Max's 'controller' Jerry and local police became suspicious, so Max hypnotized a resident called Burt Runch and directed him to dispose of the bodies. Max's actions were finally discovered and he was de-activated (losing Runch, Jerry, and several policemen 'inside' him), re-programmed and installed to run Pringles Department Store. However, the manager of the store, Gywn, managed to trigger a backup mechanism, re-activating Max's sentience, and before long he had deliberately burnt out his I.F. module and re-created the 13th Floor, this time accesible via the top of an escalator.
By this point, the strip had been running in Eagle for some time. The horror theme had been dropped in favour of more generic action-oriented stories - Max's character had been humanised, and he now saw anybody as a potential Pringle's customer, and thus a 'tenant' deserving of his care rather than death. Max uncovered secret activity by MI5 within the store, and programmed to be a patriotic computer, offered the 13th's floors services to MI5 for purposes such as interrogation, and even created a pocket-size version of himself, Minimax, to go on spy missions accompanyed by the (hypnotized) local MI5 director, Auberon Hedges.
Max eventually became homesick and used his government contacts to arrange a return to Maxwell Tower, where he yet again resumed punishing people he felt harmed his tenants. Eventually, his 13th floor suffered a fault which caused its inhabitants to 'escape', resulting the block burning down and the strip ending. Max was supposedly installed in the King's Reach Tower headquarters of the Eagle comic. He was then portrayed as the comic's editor, with few 13th floor references, until the comic's relaunch in 1991.