How to succeed at Defender  <work in progress>

  • Defender Marathon Gauntlet challenge at the WPU- HERE

Doug Mahugh’s Complete Defender Manual, written in the early 80s and critiqued by Larry DeMar/Eugene Jarvis-

The Guidebook’s resident Robotron Extreme Master just so happens to be an Extreme Master at Defender.  Spriggsy is from the UK and is kind enough to take us on a journey to explore one of the most historically significant video games of all time.

Don’t try this alone-

Observe the Master players-

Defender Enemies- (courtesy of Kai Middleton)

  • Strength- strength in numbers.  And sometimes they go a little crazy and throw out a hail of bullets when they’re going for the humanoid.
  • Weakness- they conveniently line up near the ground where you can cruise along and shoot them.


  • Strength- they jump around a lot.  Their attack vector overlaid with the attack vector of the other enemies is much more complicated to deal with
  • Weakness- the international date line, they bunch up and can be shot en masse, vulnerable to being shot when you’re flying backwards from them


  • Strength- in addition to all the flak they put up, they’re also difficult to shoot – they seem to wiggle out of the way.
  • Weakness- their pattern is not too hard to understand


  • Strength- you don’t know how many swarmers will come out.  Also, sometimes they’re not where you want them to be when you’re ready to deal with them.  They’re like Koala’s, they can hide.
  • Weakness- well, easy to shoot


  • Strength- they can create a deadly crossfire if they’re not bunched
  • Weakness- if you wiggle up and down just right you can negate their sign wave movement and even when they’re coming right at you they are easier to shoot.
  • Weakness tip from Larry DeMar- flaw in the swarmers logic. When you pass the swarmers they will not change direction to seek you, or fire until you are a specific distance away from them. If you reverse right after passing the pack, you can follow them closely and pick them off while they continue to fly in their current direction.


  • Strength- extremely fast, flat, so very hard to shoot, fire lots of bullets, the least predictable of all the enemies, and worst of all, they MULTIPLY
  • Weakness- not many weaknesses.  Even Chuck Norris drops his other tasks to deal with baiters when they appear.

The Ship’s Laser-

  • The lasers used a pixel color which was cycled through a rainbowish sequence which was internally called “laser” color.  The scores also are painted in this same cycling color and this same sequence using the laser name was used in many games (including Robotron) following Defender. -Larry DeMar Apr 2013

The Enemy Projectiles-

  • we called them “shots” more than anything else, but we sometimes called them bullets, too. – Larry DeMar Apr 2013
  • we called them shots too (swedish: ‘skott’). And the Bombers shots/bullets we called ‘mines’ – Mikael Lindholm Apr 2013

Wave progression-

  • The waves cycle through 8 waves of differing color- Youtube
  • Wave 1- Blue
  • Wave 2- Green
  • Wave 3- Red
  • Wave 4- Orange
  • Wave 5- Yellow
  • Wave 6- Purple
  • Wave 7- Brown
  • Wave 8- Black
  • It is the general view that the game doesn’t get harder after wave 24 (3 times through the 8 waves)

Using the Radar- It’s like using the rear view mirrors in your car!

  • About the driving thang : the most important thing abiut defender is being able to predict and know exactly what is going on. To this end managing your scanner to control your environment is vital.
  • When driving its important to look ahead but you must also be aware at the same time what is behind you using mirrors. Its the same with checking the screen and scanner and getting the balance right between the two.
  • Managing what is immediately on screen but glancing at the scanner to control the other 3 quarters of the planet is the number one skill required.

Control your environment-

  • Stay low, just above ground level as thats where landers mostly inhabit.
  • Slowly move forward tapping thrust and fire.
  • Dont fly too fast, let them come to you.
  • Alternate between thrust and fire as you wont need to fly around like a maniac for the first few waves anyway.
  • Control your environment , dont let it control you.

Wave 1 to 5 walkthrough- Basics for beginners

  • Click HERE for youtube video lesson
  • Take one bit of the planet at a time as its easier to keep control of your ship and therefore surroundings
  • Don’t fly around like a maniac: slowly fly just above above ground level and prioritize getting landers one screen at a time, the other enemies can wait and can be dealt with later.
  • Fly to top of screen to deal with mutated landers
  • When pods are broken up, you can fly behind the swarmers safely
  • Try to smart bomb groups of pods that are gathered on the screen, like at beginning of wave
  • The baiters are faster than you, don’t try to outrun them.
  • Advanced- Click HERE to learn about maximizing your score on the first 4 waves
  • Novice- It is harder than it looks. Learn by doing.  Click HERE to get tips on novice gameplay
  • Kai Middleton instructional to 3/4 million with commentary and alternate strategies discussed- YOUTUBE

Lander strategy-

  • My understanding is that each lander is set to seek out a particular humanoid when that lander is deployed. If there is only 1 humanoid left, for example, then all of the landers will go after it. If there are 10 humanoids, then each lander will randomly select one of those 10 and ignore all other humanoids until it gets to its pre-selected target. (Don Hodges)
  • Per Larry DeMar (Apr 2013)- Each lander randomly targets a human when they are created.  This explains why they will pass over some humans and then pick up a different one…. The Scout behavior  is known and I think the lander must be in the pickup mode when their human gets grabbed to activate it.
  • Larry cont.- If you’re holding a human it can still be randomly picked as the target so in the case you’ve been testing they all go after it once you put it down.  I believe that in cases other than the scout (where the human became unavailable during the abduction cycle) that the landers target a new human when their human is no longer available.

Mutant strategy-

  • Walkthrough for fighting Mutants – Youtube
  • Dodging shot thing : notice 5 seconds in that I take my finger off thrust to let the shot pass me by as I am shooting humanoids. Didn’t even notice I had done it : comes naturally with practice.
  • At the start of a wave in space reverse thrust for 1-2 seconds (away from pods) then reverse back toward the pods, but stay nearer to the bottom of the screen to avoid running into mutants. When you reach the pods chances are there will be many mutants. Once there simply tap reverse to maximize amount of mutants/pods on screen and then smart bomb. Then clear up any remaining mutants using the tactics below.
  • Notice after bombing pods on wave 3 and 4 that my tactic is to fire 4 shots at a time in short bursts to concentrate my firepower. Mutants will track your horizontal position, so if you stay in the top quarter of the screen and just concentrate your fire you will hit oncoming mutants. Mutants near the bottom often pass thru to the top of the screen if you are near the top, and this helps you to group them.
  • You will notice that I often miss them : no problem : observe that i simply reverse away to get them off screen , reverse back and keep shooting, reversing, shooting, reversing, shooting until mutants cleared. Try not to let the mutants get to within half a screen length of your ship. When they get half a screen away reverse away from them, then toward them and continue picking them off.
  • Tip from Eugene Jarvis- Mutants hop around randomly a lot and typically seek your x, then your y.  They are fairly slow and pretty easy to kill unless there are a ton of them.  Quick turn around with accurate shot gets them a lot of times.

Planet Guarding Strategy-

  • Watch Radar to be aware where groups of humans are, especially when down to only a few
  • Observe Landers for movements and firing characteristics that would indicate they are going to pick up a Humanoid
  • Can carry around your last Humanoid if worried about Space
  • Kamikaze- If you need to “save” a Humanoid that is almost to the top of screen, Ram the Mutant. You’ll lose a life but save the planet.
  • Technique for reducing amount of Humanoids to make it easier to guard planet- Youtube

Space – Planet Destroyed-

  • Revisit the Mutant tips on Youtube
  • Tip from Eugene Jarvis- For swarms (of mutants) you can work the “invisible lines” in the universe where they will run away from you.   It is a discontinuity where +inifinity and – infinity lie on either side of a mathematical line in space.
  • “Invisible Date Line (IDL)” further defined by Larry DeMar- The mutants will never cross this invisible vertical line while seeking you. Thus, if you fly away from a pack of mutants they will follow you until you cross this line. At that point the will seek you by flying in the opposite direction. By staying around the line and crossing it every time they get close you can keep them on the opposite side of the world. This isn’t a winning strategy by itself because the baiters will eventually come fast and furious but you can use it to systematically trim the edges of the herd. Swarmers have a similar line which is in a different position.
  • Tip from Larry DeMar- Mutants will always track you but won’t cross the line, so it does matter which side of the line you’re on if they’re near you (hint, be on the “other” side).
  • per MOS- I’ve never used it sytematically, as a strategy when dealing with Space, either….It IS usefull sometimes in space when I want to separate Mutants from Swarmers – which is an impossible mix to deal with.

Baiter strategy-

  • Baiters are strange, and different defender players deal with them in different ways.
  • Try to shoot them as soon as they appear. As soon as i hear that whooshing noise of a baiter appearing i try to position my ship so i can kill it immediately.
  • The best player I have seen baiter wise is Mike Lindholm, so watch his youtube videos (under Mikeville66)
  • Tip from Eugene Jarvis (2012)baiters do seek a random offset, and will compute your projected destination using your current velocity.  Thats why you can “shake” the baiters off by reversing a lot.  Whole idea of baiters is to get player to move on and finish wave.  Not sit around milking or wasting time. 
  • Historical insight from Larry DeMar (2012)- They were playing a lot of Asteroids during Defender development, the tiny UFO was affectionately called a lil’ bastard…which evolved into the concept of Defender’s Baiter.

Baiters- Tip for later waves

  • Baiters start to arrive near the end of a wave.
  • If you have 4 or more enemies there is quite a gap between baiters arriving.
  • 3 or less and they arrive much quicker.
  • Leave 4 bombers on until the end (concentrate on gettin rid of landers first) and thrust towards them so that all 4 are on the screen.
  • This makes the wave easier to deal with as there are less baiters to deal with. Havin 3 or less enemies left causes the baiters to come on one after another much quicker.
  • Watch Video HERE

Gameplay nuances/glitches

  • Beware- Smartbombing pods will sometimes leave a few swarmers behind. Per GUS-  I love the randomness of that – you get a warm feeling when all 4 pods get obliterated BUT if they just scatter it angries the blood!
  • On busy waves, when carrying multiple humans.  It is possible to reverse/thrust/fire too quickly and shoot your own humanoid.  Per Spriggsy- in Newcastle you had been cheated out of something then you had been “Bumped”, and if a humanoid dies while you are carrying it people would say something along the lines of” I lost me human cos i was bumped”

Rapid firing

  • The only benefit to quick fire is if a pack of swarmers is heading quickly toward you, or you have mutants up your @$$ and you need to quickly reverse and pick off as many as possible. More control than speed, which takes time to get used to but it will be better in the long run. It’s all about control and firing accurately, rather than hit and hope.- Spriggsy

Above and Beyond Fun

Wave 191 Paradox (99-99 Max Difficulty)-

Paul Spriggs-

  • Game adjust setting 18 : starting difficulty = 99 (default would be 5 on red Rom).
  • Game adjust setting 19 : progressive difficulty = 99 (default 15).
  • The game starts ridiculously fast, as expected, however on wave 161 it slows down and i can go a whole wave without seeing a baiter, when before wave 161 they arrive every few seconds. I uploaded a youtube video, and at the end i show the game adjust screen for your perusal to prove the game started on 99-99

Don Hodges-

  • OK i have analyzed the code and here is what happens.
  • The level is loaded, and then 4 is subtracted from it. If the result is less than zero, then this result is set to zero.
  • Then the value from game adjust 1 is loaded and added to this result. If this is zero, then the subroutine aborts.
  • When game adjust 1 is set to 99 and you reach wave 161, then you get 161-4 = 157. Then 157+99 = 256 = 0 in 8 bit math. So this subroutine aborts and you get an effective diffuculty of zero.
  • The game then plays as if the Game adjust 1 setting is at zero, which is very easy of course, even easier than the default game adjust setting of 5.

The Low-Down on Pods/Swarmers

Don Hodges:  Did you know? Shooting a pod usually releases 4 to 7 swarmers, but on rare occasions it can release 1, 2, or 3 swarmers (1/256 chance each). The chances of it releasing 4 swarmers is exactly 25% (64/256), but the chances of 5, 6, or 7 swarmers is 24.6% each (63/256). The reason for this is the way the random number calculator for opening pods works.
Also, the game allows a maximum of 20 swarmers to exist at any time. So, if there are 17 swarmers in the game-world and a pod is hit, it will release a maximum of 3 swarmers.

Larry DeMar (Apr 2013): The smart bomb / Pod behavior in Defender was a bug of sorts. The inconsistent handling of the swarmers that are “inside” the pods was not intentional, and probably originally simply overlooked. The system processes a smart bomb by traversing the object list (which was a linked list of dynamic memory elements for the coders watching) and blowing up the objects that were explodable.

The swarmers are not on the list when this process begins but rather are created when each pod is exploded. The way it worked, they could sometimes be created in front of the processing and sometimes behind the processing which is the determining factor of whether the bomb takes them out. Eugene liked the variable nature of this once it was discovered so it was left alone….

In Stargate we decided to make the game more attractive by consistently killing all the swarmers in the pods. This was also done to help balance out the yllabians and firebombers that were added to the mix of wave completion. -Larry DeMar

From an article in Playboy [March 1982] about Pac-Man, Centipede and Defender.

“You should also be aware that the machine has a few little quirks due to its computer program. Its inventor, Eugene Jarvis (see page 168), says it’s those quirks that give the machine character.
‘For one thing,’ says Jarvis, ‘there’s the matter of smart-bombing the pods. Actually, the way I designed the game, there aren’t supposed to be any swarmers left , but there usually are. I like to think they’re just stunned. Second, if you reverse quickly as the swarmers go past you, you can follow them. They’ll keep going in the same direction, rather than come back at you as they’re supposed to, and you can just pick them off. Third, due to some arithmetic function of the machine, there are two invisible lines in this universe – one for mutants and one for swarmers, where if they’re coming toward you and you cross the line, they suddenly fly away from you. Then, finally, there’s the biggest computer foul-up, which is that if you should hit 1.000.000 points, it suddenly starts giving you a man for each object you hit. You can get as many as 100 men. It also gives you a whole lot of rockets and smart bombs, enough to let you play almost indefinitely.’”
[Playboy, March 1982, p. 240]

Planet Refresh question submitted by Jim Bowley: I’ve read that the team didn’t think anyone would get beyond wave3 / 60k, but
that just in case the waves were made to keep going. So I want to ask about Planet Refresh. It seems to me that ‘Space’ must have been seen as a sort of Game Over (it is to beginners) but putting Planet Refresh in there indicates that you were allowing for players who could survive several waves of space, and you were letting them back into the game? Maybe there was a period, pre-release when high scores were being achieved?

  • In the pre-release time period, I remember the crazy-legendary games played out
    on the Belden Ave. production line by Eugene and Ray Gay (The guy that did all
    of the PC board layout for Williams Pinballs and Videogames). They were hitting
    in the 60,000 – 70,000 range. I don’t think the human refresh was in the game at
    this time. -Larry DeMar, Oct 2013
  •  The human refresh was one of the last features added to the game. Although
    none of the early players were that highly skilled it was added just in case
    expert players would come along in the future that could survive many waves. The
    human refresh was to provide some measure of hope and relief such that the game
    didn’t become more and more difficult ad infinitum. -Eugene Jarvis, Oct 2013

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