Following are all of the codes, maps, and some hints for GATES OF ZENDOCON:

SPOILER WARNING: If you enjoy discovering things for yourself, you should probably stop here. This file takes a lot of the fun out of it!

General Strategies

GZ's monsters are completely predictable: Every time you play a level, they will appear in the same places, in the same sequence. In addition, the "alien helpers" and other objects in the level appear in the same places. Thus, the key to mastering a level is to first explore the level. Move your ship up and down, up and down, as you proceed through the level, so you can see everything that's there. You might have to sacrificing your ship lots of times before you manage to get the whole level explored. After you know what's there, you can develop the best strategy for getting through the level. This might involve moving your ship as little as possible to reduce risk, or it might involve moving it as much as possible so as to blow away more aliens.

The Levels

In the listing for each level, the gate(s) which exist on that level are indicated with a letter, an arrow "->", and the name of the level which that gate leads to. Different letters indicate different possible positions of the gate, as shgown in this diagram:

     |             B            |
     |           A   D        E |
     |             C            |
This is meant to be a schematic representation of the level; your ship starts out at the left and proceeds towards the right.

For example, in the first level ("BASE"), it says "A -> ZYBX, E -> RAZE". This means that there are two gates: one at position "A", and another at position "E". You have to go through two "waves" of alien attack to get to a gate at position "E".

Each level's entry also tells which "friendly aliens" can be found on that level, and where. The symbols used are as follows:

@:  "Floating Eye".  Hovers below your ship and shoots a fireball
*:  "Plasma Ball".  Hovers above and behind your ship, until you fire,
     at which point it wanders off (usually towards the closest enemy)
     and attempts to destroy enemies by touching them.
^:  "Death Arising".  Hovers above your ship and shoots a red "laser
     beam" straight up.
>:  "Sonic Dart".  Hovers above and slightly ahead of your ship and
     shoots a vertical white "sonic pulse", which moves to the right
     and enlarges as it moves away.  The result is a continuous
     triangular wave of pulses which "sweeps out" virtually everthing
     in front of your ship.
The description also tells where the alien is found. Note: You won't find the alien if your ship is already accompanied by an alien of the same type.

The levels are numbered in such a way that the gates always lead you to a higher-numbered level. Also, whenever possible consecutive levels have been given consecutive numbers. (Most levels only have one gate.)

 1. BASE: A -> ZYBX, E -> RAZE
 2. ZYBX: B -> NYXX, C -> XRXS, D -> NEAT
 3. XRXS: A -> ANEX
 4. ANEX: A -> NEAT, E -> BARE
 5. NEAT: A -> YARR
 6. YARR: B -> EYES. *: Near bottom, at end.
 7. EYES: A -> NYXX, D -> BARE
 8. NYXX: C -> ZYRB. @: Near top of screen.
 9. ZYRB: A -> SRYX
10. SRYX: A -> BARE
11. BARE: A -> STAX, D -> XRAY
As soon as possible, move the ship straight up to the top of the playfield. Do *not* move left or right. The dragon will fly into your tailjets and get killed instantly.

A description of the "real" strategy for killing the dragon is given below under level "NERB".

12. XRAY: A -> RATT.  *: Near top of screen.
13. RATT: A -> NYET
14. NYET: A -> RAZE
One easy way to get through this level is to stay on the bottom and never shoot. Of course, you don't get many points this way!

15. STAX: A -> SZZZ
16. SZZZ: A -> RAZE.  *: Middle of screen, at beginning.
17. RAZE: A -> TRYX,  B -> ROXX, C -> TRAX, D -> TERA
18. ROXX: A -> NERB
19. NERB: A -> TREY.  @: Stay above partition, after dragon.
The dragon in this level is like the one in "BARE": It can be killed only by having its "head" contact your tailjets. None of the alien helpers affects the dragon.

To slay the dragon, note that it travels on a grid of circles. It will always stay in this grid.

Here's a rough sketch:

   :       :       :       :
    '.   .' '.   .' '.   .'
     .'''.   .'''.   .'''.
   .'     '.'     '.'     '.
   :       :xxx    :       :
   '.     .'.     .'.     .'
     '...'   '...'   '...'
    .'   '. .'   '. .'   '.
   :       :       :       :

The dots, quotes, and colons represent the path of the dragon. The key is to get your ship into the position marked "xxx" in the center of one of the circles. Avoid the dragon until you can see where the "center of the circle" is, and then put your ship there when the dragon is out of the way.

Once in the center of the circle, your ship is entirely safe. After a while, the dragon's path repeats; when it comes round the circle again, it will fly through your tailjets and die.

(Actually, this doesn't always happen. Sometimes your ship is a little too far to the right and the dragon will just "chirp" a little as it goes by. If this happens, move your ship to the left a *tiny* bit and wait for him to come around again.

Note: This strategy has to be modified somewhat in "SSSS", where you get more than one dragon at a time.

20. TREY: A -> STAR.  >: Third set of partitions, top.
21. STAR: D -> SSSS, C ->BYTE.  @: First set of partitions, bottom.
The "B" gate is under the second partition. It's also sort of hard to enter.

22. SSSS: A -> BREX
The dragons in this level come in groups of two or three. This makes things more difficult, because they don't always travel on the same "grid".

The strategy is the same, but since the dragons travel on different grids, you'll have to keep moving your ship. If you can't move fast enough, use your shields -- they will get you out of the way much more quickly. (However, you'll be dead if you're caught between two dragons or caught between a dragon and the edge of the playfield.) Dodge the dragons repeatedly until you see what pattern they follow. Each one follows a repeating path. Then, kill them off one-by-one, using the method described in "NERB".

23. TERA: A -> BYTE
24. BYTE: A -> BETA.  >: Near bottom of screen.
25. BETA: B -> TRAX,  E -> NEST
26. TRAX: A -> ZEBA
27. ZEBA: A -> TRYX, E -> ROXY.  @: Near top.
28. TRYX: B -> STYX
In this level, the "floor" restricts the ship to the top half of the play-field. However, there is a "hidden feature" or "easter-egg" which allows you to access another gate "below the floor". Here's how you find it:


Immediately put on your shields and move the ship down, to kill the alien tanks. Then, start dropping bombs (using your shields when necessary to kill newly-appearing aliens). You will notice at one point the bombs appear to go through the floor. At this location is an invisible "hole" through which you can fly your ship.

It will probably take a few tries before you get through, because the hole is rather small. Once you get through, you maneuver through a couple of minor obstacles and then find the gate. It leads you to the "easter-egg level", whose name is " ". (Four blank spaces: this level, therefore, can't be accessed directly as the others can because its name cannot be entered.)

The easter-egg level is fun. It also gives you all four alien helpers: @, *, >, and ^.


29. STYX: A -> YARB
30. YARB: A -> BREX
31. ROXY: A -> NEXA
32. NEXA: A -> NEST
33. NEST: A -> EBYX
34. EBYX: A -> BREX.  *: Middle of screen (can't miss it).
35. "    ": A -> NERB.  *, @, ^, >: all near bottom, near beginning.
This is the easter-egg level. Description of level "TRYX" above tells you how to get here.

Since this level leads back to an "earlier level", it is possible to loop, and thus (in theory) to play Gates of Zendocon forever: NERB->TREY->STAR->BYTE->BETA->TRAX->ZEBA->TRYX->here->back to NERB.

36. BREX: B -> ZEST, C -> SEBB, D -> STAB.  ^: Near bottom, after
a long sequence of towers with yellow-and-gray pyramid-shaped tops.

37. ZEST: A -> ZORT.  *: Bottom of screen, under stalactite.
38. ZORT: B -> STAB, E -> BRAN
39. BRAN: A -> BROT
40. STAB: A -> BOXX.  @: Middle of screen, at beginning.
41. BOXX: C -> SEBB, E -> TENT
Here's a map of this level. "[]" represents a box which is hard to shoot, "<>" represents one which is easy. "C" and "E" show the locations of the gates.
  (left half:)
|     <><>  []  <>  []  []  <>    []    <>    []    <>  /
|     [][]  []  []  []  <>  []    []    []    []    []  \
|       <>  <>  <>  []  <>  []    []    []    []    []   \
|     [][]  []  []  <>  <>  []    []    []    <>    []   /
|       []  []  []  []  []  []    <>    []    []    []  /
  (right half:)
       /  <><><><>    <>    <><><><><><><><>[][][][]    []      |
       \  [][][][]    [][][][][][][]  <>[][][][][][]    []      |
        \ [][][][]    <>[][][][][][][]  <>[][][][][][]  []    E |
        / [][][][]          [][][][][][]  <>[][][]  [][]        |
       /  [][][][]       C  [][][][][][][]  <><><><><><>        |

42. TENT: A -> BROT.  *: Near middle.
43. SEBB: A -> SNEX.  ^: Near bottom.
44. SNEX: C -> ZAXX
Yes, the "tank/truck" objects can be destroyed! However, it's a very complex operation.
  1. Wait until the first tank is about halfway across the screen.
  2. Move behind its cannon, then down behind it after the 2-legged walker isout of the way.
  3. Follow it closely, and simultaneously maneuver the ship so that it's 3 pixels off the floor. Move almost all the way to the edge of the screen.
  4. Keep the lasers on continuously. This should kill additional walkers as they approach.
  5. As each additional tank piles up behind you, the score increments by increasing amounts. When the score is incrementing 10 at a time, the one's digit will be constant. Shortly after this happens, you will kill a walker. Just after the walker is killed, move up slightly, wait for a missile to fly just under you, then move back down into position.
  6. Continue to the end. When the screen stops scrolling, leave your ship still for a bit; the tanks will all simultaneously be destroyed.
45. ZAXX: A -> BROT
46. BROT: A -> STOB.  >: Near bottom.
So-named because of the Mandelbrot Sets used in the background?
47. STOB: A -> XTNT
48. XTNT: A -> BOTZ
49. BOTZ: A -> SNAX
50. SNAX: A -> ZETA, D -> NEAR
51. NEAR: A -> ZETA.  *: Near bottom.  @: Near top, immediately after
*.  >: Near bottom, shortly after @.

52. ZETA
This is the "penultimate level", as it were. The object is to shoot at the object which slowly moves up and down along the right edge of the screen. Every now and then, this object will "open its eye"; this is the only time when it's vulnerable. The second time you successfully hit it when its eye is open, everything on the screen blows up and you are sent to the endgame.

NOTE: If you have alien companions, they will be destroyed along with everything else! (However, they still help you get through this level.) The consequence of this is that when you face Zendocon, you always face it alone.

53. Endgame
In the final screen, you fight it out with Zendocon itself, the evil spider-monster which rules all the other aliens you've been fighting. To make it through this level, use the following procedure: Zendocon appears on the right edge of the screen and moves horizontally towards you. While firing the lasers continuously, move your ship down slowly. You will eventually find a point at which your lazer-fire makes "explosions" appear on the monster.

When Zendocon is getting close, move your ship to the left and *up* out of the way. It can touch your ship without hurting you, but you want to avoid having it cover your ship entirely. Use your shields if it's a close call.

When it starts heading back towards the right, move your ship back down to fire at Zendocon's "soft spot" again. Use your shields when necessary to keep the "eyeballs" from hitting you. After the first couple of left-right "cycles" of Zendocon's movement, you'll be able to position your ship so that you can hit the soft spot and also avoid touching the eyeballs (because Zendocon slowly drifts up as it moves back and forth.)

Using this technique, you should be able to hit Zendocon enough so that it dies after five or six repetitions of its left-right path. If you don't, it will start moving around the screen diagonally. This means it's probably too late -- but in a last-ditch effort, put on your shields and fly into its "mouth". This might do it in.

If you kill Zendocon and then "commit suicide" by crashing your ship into the floating eyes, you're given another ship and have to kill Zendocon again. If you lose your last ship in this way, you lose the game. Killing Zendocon multiple times doesn't increase your score all that much, but it's something to do if you have lots of extra ships at the end of the game.

Shortest Route From Start to Finish

Fifteen screens, plus Zendocon. There are three equally short paths from BREX to BROT:

                                   `->SEBB->SNEX->ZAXX-'       |
At BASE, take the second gate. At RAZE, take the first. At TRYX, STYX, and YARB you have no choice (disregarding the easter-egg in TRYX). At BREX, choose whichever path you like best (if you choose the upper path, take the second gate at ZORT; if you choose the middle path, take the second gate at BOXX.) From BROT to SNAX you have no choice; at SNAX take the first gate.

A typical final score for the "shortest route" is around 100,000. (Or 10,000,000 in the "hard" mode -- good luck!)

Gates of Zendocon Map:

Each level's gates are numbered left to right, top to bottom, as the terrain scrolls from left to right.

         2/  `--.
         /       ZYBX 2
        /       1/|3 `--.
       /        / |      XRXS
      /        /  |       |
     /        /   |    1 ANEX
    /        /    |  .--' |2
   /        /    NEAT     |
  /        /      |       |
  |       |      YARR     |
  |       |       |       |
  |       |    1 EYES     |
  |       |  .--' /2     /
  |      NYXX    /      /
  |     /       /      /
  |  ZYRB      /      /
  |    |      /______/
  |  SRYX    /
  |     \   /
  |      BARE 2
  |      1|  `--.
  |       |      XRAY
  |      STAX        `--.
  |       |              RATT
  |       |               |
  \      SZZZ            NYET
   \         `--.    .--'
    `----------->RAZE___ 2
                1/|3\4  `--------ROXX
                / |  \               `--.
               /  |   \                  NERB
              /   |    \_                 |
             /    |      TERA            TREY
            /     |       |          .--'
           /      |       |    2 STAR
          /       |       |  .--' |1
          |       |      BYTE    SSSS
          |       |       |       |
          |       |    1 BETA     |
          |       |  .--' |2      |
          |      TRAX     |       |
          |       |       |       |
          |    1 ZEBA     |       |
          |  .--' |2      |       |
         TRYX    ROXY     |       |
          |       |       |       |
         STYX    NEXA 1   |       |
          |       |2 `--. |       |
         YARB     |      NEST     |
          \       |       |       |
           \____  |      EBYX     |
                \ |  .--'-------<-'
              1  BREX
            .---'2| 3\___
        ZEST      |      \
       /          |       \
      /           |      STAB
     /            |       |
  ZORT            |       |
    |             |       |
    |             |    1 BOXX
    |             |  .--' |2
    |            SEBB     |
    |        .--'        TENT
    |    SNEX           /
    |     |            /
  BRAN   ZAXX         /
    `--------`--.    /
                 SNAX 2
                 1|  `--.
                  |      NEAR
                  |  .--'
-- Howard Chu @ University of Michigan