Starting with the SWAC, a commercial machine, we can see most applications were either pure mathematics, or scientific in nature: Such as searching for prime numbers; developing climatological models; the X-ray analysis of vitamin B12. Processing time was split between the Institute for Numerical Analysis, and other government agencies. It's very unlikely there were any games made for the SWAC. Next, the Whirlwind 1 was part academic, part military. It was intended to be used as a flight simulator - not a graphical one, but as something that could simulate aerodynamics and control flight instrumentation. In addition, it was used for industrial process control, air traffic control - and to demonstrate the potential of computerised air defence. However, half of the computing time available was allotted to MIT for engineering and scientific calculations - and here there is evidence for slightly less serious use. Whirwind's capabilities were quite remarkable for the time, with a generously sized CRT display capable of realtime graphics. It was demonstrated live on American television in 1951, in a Christmas episode of 'See It Now'. It even played a rendition of Jingle Bells! Later, in a 1953 film, 'Making Electrons Count', we can see Whirlwind demonstrating a bouncing ball program - it's the realtime calculation of three differential equations, but in practice the CRT traces a convincing trajectory of a ball. This demo dates to as early as 1949. But it doesn't count as a video game due to a lack of interactivity. However, some sources claim that there was a version circa late 1950 to 1951 that did have a degree of interactivity: with the player able to adjust the ball trajectory in order to make it drop through the hole. Unfortunately, there's no evidence of this: the claims are anecdotal, undated - and might be misremembered. So we must presume that the Whirlwind's Bouncing Ball was a non-interactive demo, and not a game. Next, the EDSAC at Cambridge - which we already know played host to OXO, but was far more frequently used for scientific purpose. Atomic wave functions: Astronomical equations of motion; Crystallography and the structure of myoglobin; and economic modelling. So much more than a simple game of noughts and crosses, but OXO is what we're interested in. Although I should mention - OXO is not the original name of A S Douglas' program - he referred to it as 'a game of noughts and crosses' in his 1954 thesis. (The OXO appellation seems to be a product of a preservation effort by the EDSAC Replica Project). While Douglas didn't give an exact date for the program's creation, he did specify that it ran 'circa 1952.' So for the purpose of primordiality we must assume the worst: the earliest date that we can be sure of is the end of 1952. If we wanted to be really cynical, we could take the date that Douglas submitted his thesis - March 1953. In either case, this means that OXO or noughts & crosses remains the prime candidate - but was there anything else done with the EDSAC that could take the crown? It turns out there is a whisper of another game, attested in the thesis of Stanley Gill - which was submitted in November 1952. That would put it ahead of OXO. It was a game of sheep and gates: the screen vertically divided by a fence, with two gates. A procession of sheep approach these gates, and you must open the correct one by interrupting a light beam in EDSAC's tape reader. Primitive, naturally - and sadly, there are no photos. But it qualifies on the same merits as OXO - and does so with an earlier verifiable date. But let's not draw our conclusions yet. More machines remain. The Pilot ACE at the National Physical Laboratory in Teddington, London boasted strong floating point performance, ideal for the heavy scientific computations it was used for. It was a prototype machine that wasn't particularly easy to program - but it was still fast, calculating integrals and prime numbers with aplomb. It's here that I should introduce a man named Christopher Strachey, a student of mathematics and physics at Cambridge, and by 1949 a schoolmaster at Harrow. In early 1951, he was introduced to Mike Woodger at the NPL - and given access to the Pilot ACE machine. His work here was inspired by an June 1950 article in Penguin Science News: 'A Theory of Chess and Noughts and Crosses', written by Donald Davies - the ACE project lead at NPL. The article was a mathematical breakdown of the decision making and rules that governed games like chess - part of the newly emerging field of game theory, led by computer scientists like John von Neumann. This was the dawn of artificial intelligence, and there was a great interest in teaching these so-called 'electronic brains' to think: to teach them how to play games. Strachey was a teacher, and he decided to undertake this implementation: not noughts and crosses, as that was too simple; Nor chess, for that was far too complex; Instead, he chose the intermediate game of draughts (or checkers, if you prefer). With only two types of piece (men and kings), and only half the squares traversable, it would be feasible given the confines of early computer capability. Of course, programs for these machines were planned on paper before being compiled on punched tape and executed, which meant that Strachey didn't have the luxury of debuggers, break points, or anything like that - he would have to write and check his code manually. He finished a preliminary draughts program by May 1951, but it wasn't until the 30th July that Strachey had the chance to run his program for the first time. It didn't work. However, by this time there were more capable machines out there, and the computing project at the University of Manchester had made considerable progress. They had a full-scale production machine delivered in February 1951 - the culmination of five years of development. The first of the Manchester computers was the 'Baby'. This was designed as a testbed, in much the same way as the Pilot ACE - so its practical use was limited. There were some exercises in pure mathematics: highest proper factors, long division and 'other arithmetical facilities' - but it wasn't long before the machine was rebuilt into a more expanded form. The Manchester Mark 1 was a full scale computer which, while still a prototype, started to see more serious use: Including the calculation of Mersenne primes; Investigation of the Riemann hypothesis; Symbolic logic; Ray tracing; and Laguerre functions. Even so, it was a short-lived computer, quickly replaced by its commercial version: the Ferranti Mark 1. Eventually, there would be 9 such machines made (including a later revision) - but the first Mark 1 went to the University of Manchester. Here, it served the University's computing needs until its replacement in 1959. Notable uses include calculations for the Armaments Research Establishment - the British Nuclear weapons program - and the development of 'Mark 1 Autocode': a higher-level means of programming the computer that was widely used. The Ferranti machine also saw some work relating to games: Dietrich Prinz developed the first ever chess-playing program in November 1951. It wasn't a video game - it didn't use the Williams tube display for any graphical purpose. But it was only a matter of time. Back to Christopher Strachey and his implementation of draughts: Strachey first learned of the Ferranti Mark 1 in the spring of 1951, and quickly took the opportunity to write to Alan Turing, describing his interest. In return, Strachey received a copy of Turing's infamously opaque Programming Handbook for the Manchester computer, and an invite to see the machine for himself. He first visited Manchester in July, and over the next year, between careful study of the handbook and occasional visit - he familiarised himself with the machine: Ran some programs; And forged a reputation as a formidable programmer. But as much as he had mastered the technical side, there was something of an artistic streak that ran through his work. He made the computer play music: compose love letters; And, in the summer of 1952 he successfully ran his revised draughts program - and played a video game. His implementation worked - the computer was able to 'play a complete game of Draughts at a reasonable speed'. Generously, he even took pictures of the video display and published his work.