Galaxian DX

arcade game for Commodore 64, 2021

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The aim is to clear each swarm of aliens while maximising your score, dodging
bombs and diving enemies in order to stay alive. You can only fire one bullet
at a time so make them count, if you miss you'll have to wait until the
bullet leaves the top of the screen to fire again. 

Joystick in Port 2. Player 2 uses Joystick in Port 1.

The swarm moves from side to side, shooting enemies in formation is the
easiest way to clear enemies but also scores a lot less points than hitting a
diving enemy. Unlike Galaga, the swarm is able to sense incoming shots that
they would otherwise move into and stop until they have passed.

As time goes on and the swarm is cleared, the enemies will dive at a faster
rate and more will attack at once. When a stage is completed the next stage
will begin with a faster diving rate and higher number of simultaneous
attacks/bombs than the last. 

Aliens
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Blue enemies move the slowest and have less sweeping movements making them
easily avoidable, but are nonetheless dangerous when attacking in groups or
if you get trapped on one side of the screen. Enemies from the middle row
move slightly quicker.

Purple enemies move the fastest and have wide, sweeping movements, allowing
them to target you from the opposite side of the screen.

Red enemies will generally attack alongside a flagship, mimicking the
flagship's movements and protecting it. However when they attack on their own
their speed is faster than blue but slower than purple.

Flagships
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The yellow flagships are the key to both scoring large amounts of points, and
to calming the swarm. As time passes and more enemies are killed, enemies
attack in greater numbers and can drop more bombs. However, killing a
flagship calms the swarm for a period, allowing you to pick them off in
formation while they recover.

To score maximum points from a flagship you must take out the red escort
aliens first, and then the flagship. Taking out two escorts then the flagship
will net 800 points, a large amount in a low-scoring and tricky game like
Galaxian. However depending on their angle of attack it might be wise to
allow the flagship and convoy to pass and wait for a better opportunity.

Aliens that fly past you off the bottom of the screen (or abandon their attack
off the side of the screen) will rejoin the swarm from the top. However an
unaccompanied flagship will leave the stage and fill a gap in the top row on
the next, meaning there could be up to four flagships at the start of a
stage.

Aggression
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When the swarm is almost clear they will switch to ultra-aggressive mode and
continually attack with erratic movements and loop-the-loops.

Co-op Mode
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In two-player mode you play at the same time, sharing the three lives. You
both work as a team to clear the level while competing for points. The last
life can only be lost by the player who is losing at the time. 

Speedrun
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Attempt to clear the first stage in the fastest time possible. Current record
is 50.22 seconds by Eric Akeson.

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Some useful keyboard shortcuts
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       [PAUSE] - stop/continue game
          [F9] - quick load game state
         [F12] - quick save game state (still stored after leaving the site)
         [F10] - toggle performance meter
         [F11] - toggle fullscreen mode
  [ScrollLock] - quick switch control ports
    [PageDown] - make a screenshot (320x200)