It was only going to be so long before retromania – the habit of repackaging the past to entertain us in the present – outgrew the traditional spheres of film and music and ventured beyond. Two Fringe productions succeed in applying this trend to a highly niche arena: that of technology-aided fantasy adventures from the 80s and 90s.

John Robertson's The Dark Room (●●●●) is a deliciously fiendish recreation of the text-based adventure games that ran on the earliest home-gaming systems. Using the setting of 'a dark room' as an audience member's starting point, Robertson presents them with a series of actions that vary in sensibleness (they range from 'turn on the light switch' to 'tap your heels for Joseph Stalin') but not in end result: the player is invariably shunted back to the dark room, until such time as they inexplicably die. Using such brutal methodology, Robertson easily ploughs through a good chunk of his audience in each show, and his high velocity delivery and lo-fi tech set-up means things tear along at an exhilarating pace.

Knightmare Live! (●●●), on the other hand, plays a long game, transporting one plucky volunteer into the world of the cult 90s TV show in which a group of children guided one of their number through a virtual reality dungeon. The Knightmare Live! team have gone all out in transforming VR trickery into practical special effects, and their adoration for the source material is obvious.

But where The Dark Room succeeds on John Robertson's own megalomaniacal personality, Knightmare Live! stumbles by spreading its talent base too thin. The resident performers are spot on, but they, the audience and the poor sod being guided around the maze are at the mercy of whatever guest comedians are drafted in to assist. And some lacklustre co-hosting will result in an unsatisfying show.

The Dark Room, Underbelly, Cowgate, 0844 545 8252, until 25 Aug (not 14), 8.40pm, £9–£10 (£8–£9); Knightmare Live!, Gilded Balloon Teviot, 622 6552, until 25 Aug (not 14), 5.30pm, £10.50–£11.50 (£9.50–£10.50).