The true claimant to the title of first "video game" or "computer game" keeps getting revised every few years: people thinking of games they've actually played in the arcades (the sun source of all video gaming, right?) will name Pong ('72), not realising Nolan Bushnell (Mr. Atari) released Computer Space a year earlier ('71) (two months behind Galaxy Game, the first coin-op) nor realising that it was itself a conversion of MIT's Spacewar! created a decade earlier ('61) over in a university mainframe / minicomputer setting (the sun source of all computer gaming, right?)
Then someone points out Higinbotham's pre-Pong Oscilloscope Tennis for Two ('58), which is challenged by the tic-tac-toe-playing OXO ('52), which is in turn dethroned by NIM (May '51, six months prior to Dietrich Prinz's first chess-playing implementation.)
It's looking like the book is finally being closed with Thomas T. Goldsmith Jr. and Estle Ray Mann's 1947 "Cathode Ray Tube Amusement Device", as anyone else who knows any different is probably long since dead and forgotten.
The history of gamebooks is similarly twisty. (One might arrive at a more universal truth by omitting some extraneous words and just asserting that "history... is... twisty.") Joe Devers' first Lone Wolf book was printed in 1984, while Steve Jackson and Ian Livingstone collaborated on the first Fighting Fantasy gamebook, the Warlock of Firetop Mountain, in 1982... but by this time gamebooks (and their pen-and-paper RPG analogues, the so-called "solitaire adventures" Flying Buffalo promoted for Tunnels & Trolls) were already big business, following the model set by the Choose Your Own Adventure series since its launch in 1979. And yet CYOA was not sui generis -- gamebook 62, Sugarcane Island, rather than being the sixty-somethingth such book written in the vicinity of its print date in 1986, actually had been sitting in a drawer awaiting republication since its earlier printing a decade earlier in The Adventures of You series, though it was written seven years still prior back in '69! Even Sweden had enjoyed its Den mystiska påsen in 1970, while Dennis Guerrier had published no fewer than four gamebooks in '69. The illustrated Lucky Les first had his adventures printed in 1967, the same year in which Oulipo author Raymond Queneau shared his Un conte à votre façon (A Story As You Like It), generally accepted to be The First Work Of Hyperfiction... but only to those unaware of Julio Cortázar's Hopscotch, written in Spanish in '63 and translated into English in '66.
We'll lightly tiptoe past Vladimir Nabokov's work on Pale Fire in 1962 (Wikipedia reports "In 1969, the information-technology researcher Ted Nelson obtained permission from the novel's publishers to use it for a hypertext demonstration at Brown University") and ignore the eerily similar educational materials cranked out by TutorText since 1958, but that's a point we won't hammer on since the time machine remains pointed firmly back as we continue to regress all the way to 1941 when Jorge Luis Borges didn't only describe hyperfiction in his Examen de la obra de Herbert Quain (1941, translated by Anthony Kerrigan to English in 1962 as An Examination of the Work of Herbert Quain) but demonstrated it in El Jardín de senderos que se bifurcan (The Garden of Forking Paths).
If there are any earlier claimants to the legacy, they're keeping mum, perhaps not wanting to be sucked down into our mire. Who knows -- perhaps some academic will find an interactive option in the margin of the Bayeux Tapestry or will decipher Linear A or Mayan glyphs to be references to paragraph numbers. Do we know where we're going? Heck no, but perhaps at least we enjoy a slightly better idea of where we've been, a wild, bumpy and altogether improbable ride from the bold and exciting literary avant-garde to dry and mundane pedagogical tools to a medium considered only suitable for children's escapist power fantasies (and on to hyperfiction, an uncanny synthesis of two earlier steps: dry and mundane avant-garde literature. Go figure!)