Alien Sector

It's Metroid before Metroid.

I'm your friend!

Easter Egg#

Enter Service Mode, then press Right to change the sound effect to 01. Press the service button to display the screen calibration test grid, then press Left (x4), Right, Left (x2), Right (x5), Fire.

Invincibility Dip Switch#

Dip Switch B8 (Listed as "unused" in the game's manual and in MAME) originally enabled player invincibility. The game still loads this dip switch's value at DEB3...

DEB3: B6 42 5B         LDA   $425B ;Set A to Unknown Dip Switch value.
DEB6: 20 01            BRA   $DEB9  ;Branch to player damage subroutine (Ignore value of dip switch)
DEB8: 39               RTS          ;End of subroutine.

...but the BRA opcode needs to be a BEQ for the dip switch to work. Put the following code in aliensec.xml to restore this dip switch's functionality:

  <cheat desc="Restore Invincibility Dip Switch">
    <script state="run">
      <action>maincpu.mb@DEB6=27</action>
    </script>
    <script state="off">
      <action>maincpu.mb@DEB6=20</action>
    </script>
  </cheat>

Developer Credits#

If you enter your name as one of the following on the high-score list, you'll get a multicolored rainbow flashing effect for 8.5 seconds:

Unused Graphics#

Backgrounds#

Put the following codes in aliensec.xml to change the first background's graphics and palette:

  <cheat desc="Change Background 1 Graphic">
    <parameter min="32" max="224" step="16"/>
    <script state="run">
      <action>maincpu.mb@E7BB=param</action>
    </script>
    <script state="off">
      <action>maincpu.mb@E7BB=10</action>
    </script>
  </cheat>

  <cheat desc="Change Background 1 Palette">
    <parameter>
      <item value="0x70">Palette 1</item>
      <item value="0x74">Palette 2</item>
      <item value="0x78">Palette 3</item>
      <item value="0x7C">Palette 4</item>
      <item value="0x80">Palette 5</item>
      <item value="0x84">Palette 6</item>
      <item value="0x88">Palette 7</item>
      <item value="0x8C">Palette 8</item>
      <item value="0x90">Palette 9</item>
      <item value="0x94">Palette 10</item>
    </parameter>
    <script state="run">
      <action>maincpu.mb@E7BC=param</action>
    </script>
    <script state="run">
      <action>maincpu.mb@E7BC=70</action>
    </script>
  </cheat>

ID	Graphic	Notes
80		An alternate version of the first floor background - .
90		Another version of the first floor background, this one separating the holes with vertical rails.
A0		A slightly darker version of the second floor background -
B0		This unused background uses a copy of the foreground graphics from Stage 1, 4, and 7.
C0		Rocky pillars separated by black space.
D0		An alternate version of the fourth floor background - - with fewer rivets and more vents.
E0		A background of intersecting vines that doesn't resemble anything seen in the final game.

Other#

A few character graphics are unused, including a skull (to count the number of Paccets killed?), some kind of vertical meter, and a tower or something.

Used	Alt

There's an alternate version of the stage maps in the second background graphics ROM. The buildings are saucer-shaped instead of rectangular, and the boss graphic at the bottom more closely resembles what the game's bosses actually look like.

A few unused blocks for the tileset used in Stages 2, 5, and 7. The cracked graphics are close to the ones used in Stage 3 and 6, while the 16x16 blocks doesn't match the mechanical style of the rest of the tileset.

Big cracked blocks and spheres that don't match up with any of the used tilesets.

Early	Final

Early graphics for the first three hidden bonus items.

References#