The Making Of Defender

It’s hard to imagine a time when every game – no matter how simple the concept – felt fresh and new. But it once existed. Take, for example, Defender, designed by gaming legend Eugene Jarvis. For the uninitiated (and if you’re one such person, are you sure you’re reading the right magazine?), Defender is a wraparound side-scrolling shooter, with a small cast of deviously designed enemies, and a defend-and-rescue theme. The aim is to stop Lander aliens making off with your small crop of humans, carelessly exposing themselves on the stark planet’s surface. When a Lander snags a human, it rises to the top of the screen, consumes it, becomes a crazed Mutant, and comes after you. Lose all your guys and the planet explodes, driving the point home that you’re rubbish and that Defender is one tough cookie.

In these enlightened times, we’ve seen hundreds of side-scrolling shooters, but when Defender appeared, it was so revolutionary, so different, and had such complex controls that many assumed it would flop. But eventual strong sales and many sequels and remakes (see Stuart Campbell’s The Definitive Defender in issue 29 for an overview) subsequently confirmed its legacy. However, it’s the original Defender that excites gamers most, with its mix of relentless, ruthless enemies, fine-tuned controls and on-a-knife-edge gameplay.

What its fans perhaps don’t realise is that Defender wasn’t as original as it seemed at the time, and it evolved from an early game mash-up. “I was strongly influenced by Space Invaders and Asteroids, and thought we’d put the two together and create an even greater game,” laughs designer Eugene Jarvis, amused by the naivety of his younger self. “But the practical realisation of that was a real pain in the ass…”

First, hardware considerations caused problems. “Back then, games were black and white, with plastic transparent overlays for colouring different screen elements,” he says. “So we thought, ‘What’s the future here?’ We decided four colours would be enough, but we wanted this system to be for the future, so we did 16. I mean, who would ever need more than that? Sixteen colours was way more than would ever be utilised in a game.”

Resolution was boosted from the industry norm of 256x256 to 320x256, because “screens are wider than they are tall, so this gave us a better aspect ratio and the potential for a better-looking game”. Also, due to the team “not really knowing anything about hardware”, the decision was made to utilise a system that moved objects in software rather than hardware – commonplace today, but rare at the time. “The computer had to write the pixels to the screen for every object, which was costly, meaning we couldn’t put much on the screen,” explains Eugene. This fact alone drove various design considerations for Defender.

We ask Eugene how Defender’s gameplay came to be, and he notes how games were so simple in that era that you could throw a concept up on the screen in a couple of weeks and play with it. He recalls various concepts were trialled, with the first basically being a Space Invaders rip-off. “You moved a little missile base, but instead of just shooting upwards, you had buttons to shoot diagonally! We thought this was going to be the greatest thing ever, but after a week or two we figured out that it wasn’t much fun [laughs].”

For the next iteration, Asteroids was wheeled out. Unfortunately, Eugene’s hardware was raster-based, hampering the graphics. “We wanted to have an Asteroids-type ship that would rotate, but it looked rubbish, because you’d rotate it and the pixels were all jaggy,” recalls Eugene. “So we thought we’d make it round ’cause if it’s round and you rotated it, nothing could go wrong.”

Unfortunately, this cunning plan didn’t lead to the mega-game the team hoped for. “We had this cursor that moved around and showed where you were going to shoot. We fooled around with this for a few days before figuring that it sucked,” says Eugene. “We realised Asteroids without the vectors and spinning thing was just a bad version of Asteroids…” The team also recognised that the main problem was its ideas were too derivative. After a brainstorming session, the team decided one of the coolest aspects of Asteroids was flying off one side of the screen and appearing on the other – the wraparound effect.

“We thought you could have a game where you’d fly off the screen, but it would kind of scroll, and you’d keep flying into a bigger universe,” remembers Eugene. “That might seem obvious now, but most games in that era were on one screen, and so we thought it’d be very exciting to fly into a larger world.”

Eugene’s game had the initial spark it needed. The decision was made to fly horizontally only, to avoid the rotational problems of raster graphics, and then to take Space Invaders and flip it on its side. “You moved your ship up and down with the Space Invaders-type control as you flew sideways, and that provided the impetus for the layout – the basic geometric formation of Defender,” says Eugene. “We then threw some stuff out there. Originally, there were supposed to be Asteroids rocks – you’d shoot the rocks and they’d make little rocks. Horizontally scrolling Asteroids. And that wasn’t much fun. It was like: Man, this idea of making a videogame is a real pain in the ass [laughs].”

By this point, the team had spent six months working on the project, and, in Eugene’s words, it still sucked, but it was fun flying around the landscape. Eugene’s friend Steve Ritchie, working at Williams on acclaimed pinball titles, suggested the player should be able to fly in both directions, an idea that was duly implemented. “But there still wasn’t any real game there, and so we had to get back to the basics of what makes a cool game,” says Eugene. “In that era, games were really about survival, which is certainly the most powerful human instinct.”

Eugene realised the player needed a threat: “You can’t have a world where nothing’s wrong – there’s no challenge, no threat, no bad guy. In Space Invaders, you had the invaders – they came down, dropped bombs and killed you – they were mean. We needed some enemies…”

Somewhere along the line, the game received its moniker, Defender, and although the reasons for this are largely lost, Eugene reckons it was influenced by the idea that if you want to commit a lot of violence, you need to be justified in doing so by defending something. This way of thinking led to the team’s next major breakthrough.

“We knew we needed to make the game more complex and interesting, and so we added friendlies that weren’t you,” says Eugene. “This added depth to the play mechanic, because you weren’t just blindly shooting everything in sight, which gets monotonous – just killing, killing, killing, like manning a fire hose.”

Now, there was something to defend. A planet was added, depicted as a line of pixels, due to hardware limitations – “Maybe half the real-time was dedicated to just writing this little line on the screen,” says Eugene – and the Lander was introduced as the first bad guy. “All of a sudden, the game got interesting: you had a purpose, you were trying to protect these guys, and you had an enemy,” remarks Eugene. “But it still wasn’t that exciting.”

Although modern games are regularly criticised for placing style over substance, Eugene reckons it was the visual effects implemented by Sam Dicker, an 18- year-old self-taught programmer, that suddenly lifted Defender to a whole new level: “A lot of the game’s excitement comes from the visual effects. Sam’s genius was in making these particle effects – at the time, we didn’t know the term – whereby an interactive explosion was created upon shooting a bad guy.”

With explosions being created algorithmically, they changed depending on where bullets hit the Landers, resulting in a visual feast of on-screen fireworks. This was in marked contrast to the more typical canned ‘blam frame’ most games used. “That’s so boring, because no matter how and where you kill something, it’s always the same,”

says Eugene, who likens Sam’s effects to watching the surf – like waves, each explosion is unique. “It gave Defender an otherworldly feel. You’d be mesmerised when shooting three or four Landers at the same time, watching them blow up this way and that, and dancing around in this ballet of destruction.”

On a roll, the team took things further. Landers started grabbing humans, taking them to the top of the screen, consuming them and turning into psycho Mutants that homed in on your craft with alarming speed and accuracy. Although this made things tougher for the player, the mechanic of capture added a rescue element to the game. “After a Lander captures a human, you have this chance to get around the world, shoot it and save the man,” says Eugene.

This shift from shooting to defending to rescue aligned with Eugene’s philosophy that the best games are those that enable you to make a comeback, rather than merely offering an “inexorable downward slope towards your inevitable death”. This idea of redemption after screwing up, possibly via some heroic measure, found its way into other areas of the game. When all humans are gone, the planet explodes, leaving you surrounded by hostile Mutants, but every five rounds, the humans and planet are restored. “A player needs a chance to make a comeback,” says Eugene. “Life is like that – ups and downs – and this cyclical feel makes a game more interesting, and ensures it’s never hopeless. That feeling a gambler has, knowing there’s always a chance of hitting the jackpot with his last dollar – that’s what keeps you going.”

Because, in Eugene’s words, “you get tired of shooting the same thing after a while”, the Landers were joined by some allies. First came the Bombers, aliens that lay stationary mines in the air. “It’s interesting how the laws of physics are malleable in Defender – men fall to their deaths, mines float, and the ship can fly through the ground,” says Eugene. “But this supports the gameplay by being flexible, instead of imposing a rigid set of mechanics that would have resulted in a sterile and restrictive game.”

Subsequent enemies were designed to create new elements of play. Pods and Swarmers have different patterns of flight to Landers and come after you, rather than ground-based humans. Baiters, a hostile alien that can’t be outpaced, were a reincarnation of the Asteroids saucer, designed to stop players lingering on a level. “They’re a challenging enemy, and really great players can sit there and challenge them forever,” says Eugene. “It’s maddening for less-skilled players, but it added another element and created that time pressure, which was a big thing then – putting the player into a vice and slowly tightening it, ramping up the intensity.”

Along with offering new gaming experiences on the screen, Defender provided unique controls, which often seem alien to modern gamers. Eschewing a four-way joystick, Defender uses a Space Invaders-like control to move the ship up and down, but buttons for forward thrust and reversing direction. “Defender was maybe the first side-scrolling shooter game, and it was based on playing Space Invaders with your left hand and Asteroids with your right,” explains Eugene. “It was amazing how once you’d played Asteroids, you had to use the same buttons – players were programmed where thrust was on the left and fire was on the right.”

Eugene compares the thinking behind Defender’s controls to designing cars, saying there’s always a language to controls found in the past. In the same way an Eighties Ford wouldn’t suddenly switch the brake and accelerator, Eugene wasn’t about to make things difficult for players. However, he does admit that the original feeling was to put a four-way joystick on the left hand. “The thing is, a four-way directional controller was a new idea in arcades at the time, and we couldn’t find a reliable mechanism,” he says. “So we threw in a button to reverse, and the funny thing is, it actually feels better to me. When playing Defender on a console with a four-way joystick, it doesn’t feel right.

There’s something about the reverse button – you can just slide across the screen, and you get more control… And it was also very cost-effective.” Although the controls and difficulty caused Defender to initially be dismissed as too complex, it eventually sold over sixty thousand units, and is one of a handful of truly iconic arcade games. “I think Defender has longevity because there’s so much randomness,” says Eugene. “Every spaceship has its own little brain from a sequence of random numbers and a small amount of intelligence, and so each game is different. Ships come in different patterns, in different ways and at different times, and shoot at you in different ways. This, along with the physics-driven explosions, keeps the game fresh.”

He also notes that Defender offers a mix of adversaries, each with their own agenda and dynamics, along with different playing modes. “When the planet blows up, everything is a Mutant and the gameplay is almost completely different,” he says. “And then there’s the progression of difficulty, which provides great suspense, but that sense of redemption, where if you can just survive a couple more waves, everything will be okay. Instead of a straight line of progressive difficulty, Defender offers a rollercoaster of emotions… Plus, I think there’s maybe something about flying at breakneck speed through all this crap exploding left and right, getting a rush from the path of destruction.”

As the interview draws to a close, we wonder if there’s anything else Eugene would like to say about his classic game, and this leads to the subject of bugs, which he considers some of the really interesting aspects of Defender, notably the invisible lines that join the wraparound universe. “At that point, the enemy-seeking algorithm doesn’t work. If Mutants are chasing you and you cross this invisible line, they’ll start running away,” he says. “Great players can exploit this, grouping Mutants, making them run away, then making them come back and blasting them all.”

Other enemies have different invisible lines, and Eugene reckons this created an interesting richness that wasn’t programmed. “Enemies suddenly start running away, and you go after them and they then come back after you,” he says. “Players anthropomorphise their motivations. You don’t want to believe they’re just a bunch of random numbers, so you call them ‘scared’ or ‘mad’. To these little robotic creatures whose brains and intelligence are ten lines of computer code, you give human characteristics and moods. Some players are like, ‘Man, the Baiters are pissed off today’, and on another game, you kill them and it’s like, ‘They were afraid – I could see the fear in their eyes’.”

Another aspect of Defender was how it always ran on the bloody edge of running out of real-time, and a key design objective was to keep its crisp 60Hz frame rate rolling, ensuring no time-lag and responsive controls. “But if you explode a Pod with Swarmers in, the system momentarily bugs out, and the video gets highest priority,” explains Eugene. “The system stops processing collisions, and you can use this to your advantage to fly right through things.” He explains that seasoned players often fly round the world at breakneck speed, starving the collision detection of realtime, and appearing to get away with stuff mere mortal gamers can’t.

This in many ways recalls what Eugene spoke of earlier – of creating an open system with few parameters and not controlling every eventuality. “This is why people are still interested in Defender – every detail wasn’t scripted. When you over-script a game like a control freak, you strangle the life out of it, and it becomes finite,” concludes Eugene. “There’s no interaction and no life. Even if it’s amazing, you’ve seen it all, and it’s the same every time. But the beauty of gaming is constant interaction, the involvement of the player, and doing something meaningful, rather than just playing a video.”