Game Development Reference
In-Depth Information
Now to define the game mechanics:
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A ship is flying at the bottom of the playfield, capable of navigating only on
the x axis.
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The movement is limited to the boundaries of the playfield. When the ship
reaches the left or right boundary of the game field, it simply stops moving.
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We want to give the player the option to use either the accelerometer to
navigate the ship, or the onscreen buttons, for left and right movement.
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The ship can fire one shot per second. The player shoots by pressing an
onscreen button.
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At the bottom of the game field, there are three shields, each composed of
five cubes.
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Invaders start off with the configuration shown in Figure
12-2
, and then
move to the left for some distance, then move some distance in the positive
z direction, and then move to the right for some distance. There will be 32
invaders in total, making up four rows of eight invaders.
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Invaders will shoot randomly.
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When a shot hits the ship, the ship explodes and loses one life.
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When a shot hits a shield, the shield disappears permanently.
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When a shot hits an invader, the invader explodes and the score is increased
by 10 points.
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When all invaders are destroyed, a new wave of invaders appears, moving
slightly faster than the last wave.
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When an invader collides directly with a ship, the game is over.
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When the ship has lost all of its lives, the game is over.
That's not an overwhelming list, is it? All operations can essentially be performed in 2D (in the
x-z plane instead of the x-y plane). We'll still use 3D bounding spheres, however. If you'd like to,
you can extend the game to real 3D after we are done with the first iteration. For now, let's move
on to the backstory and art style.
Developing a Backstory and Choosing an Art Style
We'll call the game Android Invaders, in deference to Android and
Space Invaders
. That's cheap,
but we don't plan on producing an AAA title yet. In the tradition of classic shooters, like
Doom
,
the backstory will be minimal. It goes like this:
Invaders from outer space attack Earth. You are the sole person capable of
fending off the evil forces.
That was good enough for
Doom
and
Quake
, so it's good enough for Android Invaders, too.
