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The Sinclair ZX81 – A Prelude to Modern Games

written by Mark Doyle October 29, 2013

Pete Gooding takes a look back at a cultural icon, the Sinclair ZX 81, and one of it’s most memorable games – 3D Monster Maze, a game that laid firm foundations for influential masterpiece Doom.

When you have a conversation with someone about the home computers of the old days and you mention ‘Sinclair’ most people will assume you are referring to the Sinclair ZX Spectrum, a marvellous computer but let’s take pause a moment and remember that there were two Sinclair machines that made production prior to the Spectrum. I would like to take a moment to relay my own fond memories in particular of the Sinclair ZX81.

When I was a kid the word ‘computer’ conjured up an image of a huge room with wall to wall tape reels endlessly spinning and a vast array of lights and dot matrix printers. I was always intrigued by the idea of them, however, they were used in activities such as helping mankind shoot rockets into outer space and such like; never did it cross my mind that they might be used to play games on. Then one day I went with my father to our local social club one Sunday afternoon as I often did as they had a rather excellent skittle alley that I enjoyed using even though I was probably too young. This particular time however, I noticed a rather tall, square box with buttons and a glass screen on the front standing in one corner of the club. People were huddled round it and I remember much excitement surrounding the spectators who were watching some kid press the buttons and there were all sorts of strange sounds emanating from this box – I just had to know what was going on here. Two words; SPACE INVADERS, need I say more? So of course I immediately rushed up to my father demanding as many 10 pence pieces as I was allowed and joined the queue of people all waiting to play this game.


That was just the beginning of my addiction to gaming; I became obsessed with it. Shooting aliens from a space ship that I controlled was like no other kind of awesome for me. Just when I thought I had experienced addiction at its best, along came Galaxians, Pac Man, Frogger and all kinds of variations that filled amusement halls everywhere I went. I couldn’t tell you what the beach was like when we went to Dawlish on a family holiday or Weymouth or Exmouth or anywhere else like that but I sure as hell could tell you what their amusement halls were like and what the best games were. Oh the slot machines were dinosaurs; relics from the days of entertainment long gone, and I used to dream of owning such games where I could play them all day long and not have to relinquish a single 10 pence piece. But that was just a dream; a fantasy that could never happen in a million years…

A few years later when I had started secondary school, a friend of mine invited me over his house to show me something that in his own words he guaranteed I would love. Usually we played board games such as Monopoly or kicked a football around in the street but this day we went straight into his room and there sat on a desk in front of his old black and white TV was a small black box with what looked like a keyboard drawn onto it; beside this was a tape recorder that was connected to the box via a jack plug. With an ear splitting grin my friend produced a cassette tape and inserted it into the tape player; then he pressed one of the little drawn buttons on the black box; it was then that I noticed the tv screen; there was a small flashing line in the corner and when he pressed the button the line changed into the word LOAD””; he pressed another button and pressed play on the tape recorder at which point the TV looked as though it had broken. Black and white horizontal lines danced about the screen as my friend tweaked the volume levels on his tape player. After a few minutes of this I seem to remember thinking that I would rather be kicking a ball around outside – anything but this when all of a sudden the screen changed to a picture of what looked something like a clown. On the right were words that were scrolling up the screen giving the impression that this was what the clown was saying to me. It was a pivotal moment in my life. The clown was inviting someone to enter a maze – presumably my friend in order to find his way out. Not just a maze though; in this maze there lived a dinosaur, Tyrannoaurus Rex. I twigged it; this was a game, a game just like in the arcade halls. I became truly amazed as I watched my friend play this wonderful game; apparently the object was to find the exit before the monster got you. There was no sound but to me that just made the whole experience all the more atmospheric. Just by pressing some of the buttons on the flat keyboard you were able to move left turn, right turn and forwards. The walls of the maze came at you in 3D whilst you desperately tried to locate the exit. The game would put up messages at the bottom of the screen throughout the game depending on how far away from the monster you were. Messages such as REX LIES IN WAIT, HE IS HUNTING YOU, FOOTSTEPS APPROACHING and REX HAS SEEN YOU caused the heart to race or the inevitable RUN HE IS BESIDE YOU or BEHIND YOU produced many a girly squeal. But the scariest bit of all was when Rex appears and starts running towards you. That for me was a truly trouser soiling moment!


The game was called 3D Monster Maze and was just the first of many games that I experienced that unforgettable evening.  Other games followed; Space Raiders – this was Space Invaders in the comfort of your own home and you could play it over and over again it didn’t cost you any money.  I had to have one.

Naturally I procured one thanks to my ever loving parents and began to build my ZX81 games collection.  I also collected magazines and took a bit of an interest in how they worked and what made them tick.  BASIC was the name of the programming language that allowed idiots such as myself to grace many a computer shop and get messages such as ‘Peter is cool’ endlessly scrolling across the screens of whatever spare computers were available.

Computers were advertised as being educational and an asset to any home which of course is the line I gave to my parents, but let’s be honest, games was where it was at; this was all that interested me.  Even to this day though where games have mind blowing graphics and realistic gameplay, they do not give me the thrill that I experienced that evening when I encountered Rex in his lair of the 3D maze.  It was only years later that I realised something else; this game was revolutionary as it was to my knowledge the first 3D game on a home computer system in that it made the graphics into a 3D visual field for the first person perspective.  Sure, the Spectrum and the Commodore computers had 3D games but the ZX81 had it first.

The game itself was written by a man called Malcolm Evans and based on a design by J.K.Greye and was written for fun initially as computer games programming was not his job; he worked as a microprocessor scientist at Sperry Gyroscope in Bristol.  I remember an interview with him that was done in one of the many magazines of the time and the interviewer asked him how had he managed to produce 3D graphics on a machine that did not have 3D capability, to which, he answered it was easy because he didn’t know that it couldn’t – amazing and more profound than I ever realised at the time.


The maze was a simple 16 by 18 cell affair and was randomly generated with the monster lying in wait. It was also revolutionary in that it used a very basic AI which had the Rex chasing after you once it had caught sight of its prey.  I wouldn’t like to say that it was the first use of AI in a game but it was very advanced for its time; let us not forget that this was written out of pure programming enjoyment as a hobby.

The way that the clown appeared to take his hat off in a gesture of respect was a nice touch.  I think that because the hardware was so limited it forced programmers to really stretch boundaries and help the home computer game to evolve into the wonder of modern media entertainment that pleases players today.  That said, it was also proof that teams of people staffing massive software houses were simply not needed, and as the Android market continues to develop this is at last seeming to be the case once again.  It is only a personal opinion that I offer now but I feel that the best computer games that have been written over the years have been the ones of the ‘bedroom programmer’.  They have so much more in the way of character and depth.  Part of the reason for this I feel lies in the fact that those games were one person’s vision, not tainted and watered down by a whole team of other individuals all trying to pull the game in their own direction and put their stamp on it.  Modern games often become too ‘messy’; too many different menu systems and other idiosyncrasies that dilute the overall ‘whole’.

This game really put your heart into your mouth and left you on a plateau of gaming pleasure that ensured that you would come back for more.  1981 was the year that 3D Monster Maze was written. That’s 32 years ago folks, thirty two!  Way before Doom, way before Resident Evil, but you have to ask yourself would the latter games and others of that ilk be around now if not for this game?  I like to think not.

Sir Clive Sinclair and Mr Malcolm Evans, I salute you.

Peter Gooding

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