The Making of... 3D Monster Maze


A second-hand ZX81 was my first ever programmable computer and I'd spend hours typing in listings from magazines to see what they did. The games it came with in only 16K of RAM were absolutely stunning, and its limitations actually made things like 3D Monster Maze possible. The graphics were so basic they only had one speed, so it really didn't matter how big a monster you put on the screen it'd run at the same speed.

I never had 3D Monster Maze back then, but it was always the game everyone was talking about. A strangely coherent and very British experience. Needless to say when writing the article I played it extensively (possibly excessively), and even toyed with my own variant, 4D Monster Maze, which randomly used the inverted character set for 'night' levels.

Malcom Evans was lovely to talk to, I interviewed him over lunch in Bath and afterwards popped into the Edge offices to say hello. 



JK Greye Software, Sinclair ZX81, 1981

For a generation 3D Monster Maze showed that computer games could invoke emotion. Mostly panic and terror, admittedly.

Body Copy (1500 words. Roughly)

Malcolm Evans does not look like a man who creates nightmares, but then 3D Monster Maze was never meant to be a nightmare. It was never meant to have a monster. It was never even meant to be a game. At least, in the beginning.

There was no sign that when an innocent electronics engineer considering a move into programming received a new Sinclair ZX-81as a birthday present from wife Linda that it would end in shock and evisceration for a generation of nine year olds.

“It was almost a joke, actually", recalls Evans, which may have been many people’s reactions at the first sight of that tiny machine. Evans was a hardware designer in the aerospace industry, used to working with the most advanced microprocessors. By comparison the ZX-81 was little more than a toy. It did, however, offer him an opportunity. He’d been curious to have a go at writing the programs that ran on the chips he helped design, but had no real software experience. His approach to careers advice had not proved fruitful. “They turned round and said, “You’re too old to go into software.”" he recalls. Now he had his opportunity to program. He would build a maze.

“Suddenly I had this computer in front of me and I had to find something to do with it. I didn’t want to just sit there playing games on it, and producing a maze was something you could see, you could see it working.”

It was the visual aspect that cemented that decision. With only the bare machine and Sinclair’s built in BASIC it helped immeasurably if you could see errors in your program just by looking at the screen. He rapidly developed a system that could generate 16x16 square mazes, each square either corridor or wall, and display this on the screen in a top-down view. With that done, there was still more to learn. Assembly language beckoned, so Evans added a routine to display what the maze look like for someone standing inside it.

“[It was] just the next step in learning or visualisation or simply seeing what could be done. I was learning to program more than writing a game. That was why from the beginning it was in assembler not BASIC.”

Evans never intended his program to be a game, it was never for anyone else, just a learning exercise for him. A harmless experiment. Fate however was to step in when Evans met John Greye at a classical guitar club in Bristol. Greye had developed a number of ZX-81 games and was setting up a company to sell games commercially.

"I Mentioned to him in passing that I was writing this program, and he said "Has it got a monster in it?" "no". he said: "oh it might be a good idea to put a monster in it, then it might be saleable, you see. “

“I had nothing better to do, so I created a monster"

No crack of lightning, no peel of thunder, just a casual suggestion and more intellectual curiosity. Evans chose to reanimate Tyrannosaurus Rex, king of the dinosaurs. Why? The Minotaur might have been more classically apt. Perhaps Nosferatu, as a nod to the host machine’s silent black and white images. Maybe it came from a half remembered nightmare, pursued by the slavering beast, unable to escape? No. It was just handy.

“[It] was taken from one of the kids’ books”, he remembers, although sadly not which one, “Everything I ended up drawing was always from a book. Not that form, the idea.”

Despite his humble origins, Rex was a giant. Evans began his design with the last thing the poor victim would see, the monster filling the screen, lunging forwards, teeth bared. Nobody had made such a massive opponent before, but in these early days nobody knew what was and wasn’t possible. Evans was finding out, and a giant animated Tyrannosaurus, it turns out, was fine (see boxout)

Once the grisly end was set, he then made smaller images to represent the beast further and further away. The players of course would experience this sequence rather more often in the reverse order. Evans’ focus was on trying to make the graphics as smooth and fast as possible. Rex was just a vehicle to let him learn.

“I was always being accused of graphics being more important than the game itself, which is exactly right. I’ve been setting a problem, seeing if I can solve it, and then create a game out of it.  I was working out how to use the graphics all the time.” 

As there were no art packages, Rex first came to life on graph paper. Evans’ years of electronics experience allowed him to convert the black and white squares into data, which wife Linda would then type into the machine.

There was no need for side or rear views of the monster. After all. If you ducked into a side passage to hide hoping to be spared, you’d be in for a shock. The AI had only one mission.

“He’s aiming straight at you all the time.“, Evans remembers, “He is quite intelligent. It’s not like Pac Man, just random. He’s after you.”

Rex’s behavior developed apart from his image as a rather less intimidating single blip in the 2D program written to originally test the maze generation. Once Evans was happy that the monster’s hunting was flawless, he was brought him into the 3D world.

Rex took full and immediate advantage of this opportunity, and devoured his creator.

“Quite a few times the monster would come up to me with absolutely no warning whatsoever and I'd jump out of my skin”, chuckles Evans. His wife’s reaction to his plight was unsympathetic, “She'd burst out laughing.". The realization had dawned though that he had literally created a monster.

"It was then I thought, right, I've got to put something more into it to actually warn people because its so sudden. If you were facing in the wrong direction, it was just there, you get no indication whatsoever, so I started then putting messages saying where he was."

It may have reduced the shock when Rex pounced on the author, but players panicked into flight by the sudden announcement that ‘HE HAS SEEN YOU’ when they hadn’t seen him might dispute the calming effect of these messages.

This voracious predator had altered the feel of the program dramatically. The first person view gained an air of claustrophobic menace. The focus had shifted. It used to show what was in front, now it didn’t show what was behind. The simple left, right and forward controls were suddenly distinctly lacking ‘reverse’. There was no doubt about it, he had a game. Evans showed his progress to Greye.

“He said, right, all it needs is a title screen now and we can probably sell it. I thought “let’s make it interesting …” Why on Earth would a player be in a maze being chased by a dinosaur? Because a clown suggested it, of course. Evans produced an elaborate scrolling text introduction, a Roll up! Roll up! carnival pitch. “It was more than a clown, it was a ringmaster”, claims Evans. “That was put in because I was worried that it could frighten someone”, which in retrospect is perhaps a slight understatement. “It was half-serious because it carries on to say the management take no responsibility just to be on the safe side.” It certainly added to the surrealism, as though this were an episode of The Avengers or The Twilight Zone.

One last touch added a psychological twist to the ending. When (and not ‘if’, it was inevitable) the player was eaten, they were offered the chance to play again or quit. However, there was only a fifty percent chance that their ‘appeal’ would be granted. Otherwise, they’d find themselves plunged straight back in the nightmare maze. Evans’ justification?

“There’s something wicked about me, I think. I thought if you’re stuck in the maze, lets make it real. And say OK, You ARE stuck it in the maze. Perhaps if they want to get out they can, but if not they can stay in there and they have to pull the plug out.”

Whatever the reasoning, Evans had written the game that would define the machine. Appearing early in the ZX-81s life, it had a polish and attention to detail that made it stand out from the crowd. Three years on from its release it was still selling in huge numbers, giving gamers a taste of what the future had to offer.

What about its place in history? Was 3D Monster Maze the original first person corridor shooter? Given that it was never released in the USA, its influence on Doom et al is probably less than we’d like to think. There’s also the critical difference – the player isn’t armed. Evans never considered the possibility of fighting back against Rex. Who would? That would be ridiculous. This is not to deny its place in gaming history, just that we might be looking at the wrong branch of the gaming tree.

Ask any player, and they’ll tell you what main 3D Monster Maze was about. Fear, panic, terror, facing an implacable, relentless foe who’s going to get you in the end. At its heart 3D Monster Maze is the original survival horror game. Perhaps the last thing anyone, even its author, expected to find when they first picked up that innocent looking little plastic cigar box.


Evans animated ringmaster was nearly even more sinister, “I had great difficulty when he took his hat off and bowed. It always looked like he took his head off as well.”

Add other images to taste from original supply. Lots of monster shots and some teeth, I imagine.

Boxout – Low Resolution, High Performance

(Two 150 word boxouts? Why not try a single 350 word one instead?)

The ZX81 didn’t really have pixel graphics; Sir Clive’s machine only understood text. As a compromise however the character set included several blocky graphics characters along with the usual letters and symbols. When stitched together these made pictures, like teletext but with an even lower resolution. This had the advantage that there was no speed difference between drawing a giant Tyrannosaurus Rex and a page of words. To the ZX81 they were both just character strings. As a  bonus, screens could be constructed in memory and then switched into view instantly avoiding any flickering.

The individual pixels of later machines struggled to match this power. “I wanted to do 3D Monster Maze on the Spectrum, and I came to the conclusion that it couldn’t be done with the speed or the graphics.“ Evans recalls. It wasn’t the maze, it was Rex. He was just too damn big to survive in an age of colour and high resolution better adapted to small, scurrying sprites. It wasn’t until the 16-bit era started that such giant opponents could once again roam the earth.

(Image - 3D Escape)

Evans made several attempts to recreate his monster in later games. 3D Escape on the Spectrum uses a top-down maze, which is essentially expanded from the 2D maze used to develop Rex’s hunting abilities. It features a number of different creatures to make up for the wider perspective, however the first level however begins with just the player and Rex.

(Image - Corridors of Genon)

Corridors of Genon featured a cylindrical maze occupied by short, Q*Bert like creatures that would essentially throw up on you. These enemies were the largest creatures Evans could satisfactorily animate on the screen, something of a comedown, and despite increasing numbers to make up for their small stature, rather more comical than terrifying.

(Image - Spectrum Monster Maze)

The game did eventually make its way on to the Spectrum some 16 years after its original release courtesy of ZX81 emulation expert Russell Marks. Did he have problems reanimating Evans’ monster?  Frankly, yes. Despite the Spectrum’s increased raw grunt the graphics still posed problems, as it lacked enough speed to redraw the entire screen each frame. “It wasn't too bad, but I remember it looking a bit rough on the screen you get when you find the exit.”, Marks recalls.