© 2007, Blade Edge Software
Drop Zone
Design Document v1
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© 2007, Blade Edge Software
Overview
Game Concept
Players use Drop Ships to control ground unit movement over a map in order to seize territories
and destroy the opponent(s) base.
Game Setting and Genre
The game world in Drop Zone will be set in the future. As of right now, Drop Zone has no singleplayer aspect, so no backstory is needed. The future setting is for the use of hover-jet unit
transports, and also opens up interesting unit possibilities. The game is a top-down 2D
action/strategy game with 3D graphical elements.
Platform Support
The game will be initially designed for keyboard/mouse control on the PC, Mac and Linux
platforms. Control will attempt to be adapted for XBox 360 controllers as well.
Technology
The game will be developed using Torque Game Builder, with Torsion for source code editing.
Gameplay Overview
Game Setup
Games start on a 4-sided map that is fully navigable by each player. For simplicity sake, we will
only have 2 players (up to 4-16 players, co-op online play, etc can be added later). Each player
has an Airbase at opposing ends of the map. This Airbase contains all the key elements for a
player's strategy, including unit Barracks and Hospital, an Academy, Repair Hangar, Landing
Field and air/ground defensive emplacements. Each player begins with 4 Drop Ships at their
disposal, of which only one can be flown at any given time (a co-op mode could allow teams of up
to 4 players to fly each Drop Ship) – each Drop Ship is the same, so it's like having 4 lives.
Players do not start with any units.
Fig. 1 – Basic Airbase design
The Drop Ships
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Drop Ships are housed at the player's Airbase on the Landing Field. When the Drop Ship in use
is landed on the Landing Field, the player can select a new Drop Ship to control if they wish.
Control
To control the Drop Ship, the player uses a combination of WASD and arrow keys (the Xbox 360
controller will utilize both analog joysticks). The WASD keys control pitch and lateral thrust, while
the arrow keys control rotation and altitude. To be more specific: the W key pitches the nose
down for forward flight, and the S key pitches the nose up for reverse flight. The A key provides
left lateral thrust (strafing), while the D key provides right lateral thrust. The Up Arrow makes the
dropship rise higher, the Down Arrow makes it sink lower. The Left Arrow rotates the craft to the
left, and the Right Arrow rotates the craft right.
Movement
The Drop Ship is not a fixed object that the game world moves around. It is instead a combination
of both fixed and free movement. Initially a Drop Ship is free to move about the screen, however
when it approaches the edge of the screen, the game world starts to pan in the direction the Drop
Ship is headed. This panning effect quickly moves the camera to place the Drop Ship in the
center of the screen so that it appears that the Drop Ship is a fixed object and the world is
moving, when it is in fact both. If the Drop Ship slows or reverses direction, the screen lock is
broken and the Drop Ship is again freed to move about the screen until it hits another edge.
Damage
Drop Ships can receive damage from ground-based defensive emplacements (AAA, SAM) as
well as from enemy Drop Ships (carrying units) and ground units. When a Drop Ship is damaged,
its overall performance is lessened (control, speed, maneuverability) and it needs to be taken to
the Repair Hangar for servicing. The Repair Hangar can hold as many Drop Ships as the player
has at their disposal, but it can only service one at a time. When a Drop Ship is done being
serviced, it gets towed back out to the Landing Field, where it can be swapped back into service.
Drop Ships destroyed in flight will cause the loss of all units on board, and the camera will pan
back to the player's Airbase for selection of a new Drop Ship. If none remain, that player loses by
forfeit. (Drop Ships that are killed in co-op mode could re-spawn after a set time, but never more
than there are players currently on a team)
Attack
Drop Ships are not offensive platforms, however when loaded up with certain units, gun ports will
be automatically manned, allowing the Drop Ship to return fire if fired upon. This is highly
ineffective against ground emplacements and even other Drop Ships however, and more of a
means of helping to secure a hot Drop Zone during landing.
Flying
Since this is a jet hovercraft, it moves in the same way the space ship in Asteroids does. If the
player lowers the nose and enters into forward flight, releasing the Up Arrow will level the Drop
Ship but will not stop its forward momentum. Eventually, air friction will cause the Drop Ship to
stop, but in order to quickly cancel its forward flight the player has to pitch the nose up. The same
applies for both lateral thrust and rotation, although in each case the less momentum generated
the shorter it will take for the ship to stop on its own. Forward/backwards and lateral motions take
longer to cancel out than rotation. Only altitude changes do not require the cancellation of
generated momentum. As the player gains altitude, the map grows smaller in the screen, and
larger as the player sinks. Drop Ships will have a maximum altitude. The weight of a Drop Ship,
which is dependent on the number and types of units loaded, will also affect speed and
maneuverability.
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In the UI HUD there will be an Altitude Bar as well as a Terrain Level Bar superimposed atop
each other. As the player flies the Altitude Bar will reflect any changes the player makes in their
height, while the Terrain Level Bar will reflect any changes in ground height. If the Terrain Level
Bar ever hits the Altitude Bar, the player will crash (given enough forward velocity – at the very
least damage will be caused unless velocity is near zero for a landing). The rate at which the
Drop Ship changes altitude directly depends on its velocity (forward, backward or lateral).
Therefore to land safely the Drop Ship must be traveling at near zero velocity (near zero means
within a certain speed range, not necessarily exactly 0mph). This means that the fastest way to
land a Drop Ship is to come in fast while dropping, flaring the nose up at the last possible moment
to kill velocity while still descending for a soft touch-down.
While in transit, the Drop Ship will consume fuel. The rate at which fuel is consumed is based
solely upon the weight of the Drop Ship, which in turn is governed by the amount and types of
units loaded aboard. An overlay option will be available to let the player see the Drop Ship's
current range based on fuel level and load. To refuel, a player simply has to land the Drop Ship at
the Landing Field on their Airbase to begin the refueling process. The amount of fuel needed to
be replaced dictates the length of the refueling process. Players can also use Refueling Stations,
which will be discussed later. Drop Ships that run out of fuel will crash with all units aboard, and
the camera will pan back to the player's base so they can select a new Drop Ship to fly. If none
remain, that player loses by forfeit. (Again, co-op rules will differ)
The Units
Again, to keep things simple only two units will be used for initial game design – the Engineer and
the Grunt. Units are trained at the Academy and housed in the Barracks/Hospital. The important
thing to understand about units is that players do not have direct control over them, which will be
explained further in the following sections
Training
Units are trained in the Academy which regularly spits out new units, which then move over to an
empty Barracks building (of which there are several) closest to the Landing Field. While a player
is on the ground at their Landing Field, they can change unit training priorities, which are sliders
that control how often the Academy creates one unit over another. The amount of time it takes for
the Academy to create units depends on the Morale of the player's units, which will be discussed
later. The Academy will stop training units when the Barracks are full. The amount of units a
player can barrack is capped equally for both players at the start of the game. This cap can be
increased by controlling Battle Zones, discussed later.
Loading
Units are loaded onto a Drop Ship in two locations, the Landing Field and a Drop Zone. When the
active Drop Ship is on the ground in the Landing Field, the player can drag and select units in a
Barracks building and click a UI button to start the units moving towards the Drop Ship – units do
not instantly transfer. When they reach it, they will automatically load. The more units, the longer
the loading process will take. Upon units leaving the Barracks, the player also can start the
transfer of any units barracked in buildings farther from the airfield to buildings closer to the
airfield. When in a Drop Zone, any units also in the Drop Zone will be selectable for loading onto
the Drop Ship and will load in the same manner as described for the Airbase.
A UI display will let the player know how full the Drop Ship is. Some units will take up more space
than others, and some will move faster than others. The more units and the combination of units
loaded will increase the weight of the Drop Ship.
Healing
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Units that are med-evac'd to the Airbase will be transferred to the Hospital, where they will heal.
The transfer process takes time depending on the amount of wounded being transported. The
same goes for the healing process – the more wounded a unit the longer it will take to heal. When
back to health, the unit will be discharged and transfer to the Barracks building closest to the
Landing Field. Hospitals can only take on so many units before becoming overwhelmed. If more
units arrive than there is space for, more severely-wounded units will be triaged. The level of
health that triggers a med-evac call can be set per-unit at the Hospital when the player is on the
ground at their Landing Field, as can the level of health at which a unit is discharged, in case they
need to be cycled out faster. Units that are wounded very seriously and can no longer walk will
need to be driven to the Hospital by ambulance, which can only take a few units at a time and
could lengthen the unloading process.
The Grunt
A Grunt is the game's attack unit. When loaded into a Drop Ship, they take up gun ports and
return any fire directed at them. When deployed on the ground, they hold defensive positions or
attack any enemy Grunts they encounter while on Patrol.
The Engineer
An Engineer is used to build offensive and defensive structures on the map. They cannot attack,
and will always remain out of the line of fire unless they are constructing something, in which
case they will keep working until they are killed. They won't be targets unless they are the last
units remaining in a battle or they are busy building a structure. When deployed, they will Patrol to
the nearest Build Pad.
Ground Conflicts
All major conflicts in the game will take place on the ground, as there are no air units besides the
Drop Ships.
Drop Zones
Drop Zones are marked areas on the terrain where a Drop Ship can land to deploy units. At the
start of each game, all Drop Zones are uncontrolled. In order to gain control of a Drop Zone, the
player must secure it. When a Drop Ship lands in a Drop Zone, eight (8) areas ringing the Drop
Zone are highlighted. By clicking on units and dragging them to a highlighted area, the player
assigns that unit to secure the Drop Zone. When at least four (4) of the eight (8) areas are
occupied by units, the entire Drop Zone is secured. More units can be placed to further secure
the area. Secured Drop Zones are highlighted in the player's color. This does not by itself,
however, prevent enemies from landing and deploying units. There are two Drop Zones found in
every Battle Zone, one at each end, except for Battle Zones connected to Airbases. In this case,
Drop Zones are only located at the opposite end of the Battle Zone from the Airbase.
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If ground units Patrol to a Drop Zone on the opposite side of a Battle Zone, they will automatically
secure the Drop Zone with the maximum number of units available to fill the perimeter slots.
Fig. 2 – Battle Zones (blue) with their random IDs and Drop Zones (red)
Battle Zones
Battle Zones are rectangular areas of the map where ground units will attack each other. Battle
Zones are outlined both on the terrain itself and the mini-map. Units can only attack units in the
same Battle Zone. At the end of each Battle Zone can be attached at least one and up to three
adjoining Battle Zones. In order to gain control of a Battle Zone, the player must secure the Drop
Zones on either side (because of this, Battle Zones attached to Airbases always belong to the
player that controls that Airbase). Controlling Battle Zones is important for several reasons:
1. Units can only move on the ground in Battle Zones. In addition, moving to an adjacent
Battle Zone can only be done if the Drop Zone in each Battle Zone that is adjacent to the
edge to be crossed is controlled by the player.
2. Controlling Battle Zones allows the player to construct defenses (AA and ground
emplacements) along with supply facilities to hinder their opponent's operations and
improve theirs.
3. The more Battle Zones a player controls, the higher their unit morale. The higher a
player's unit morale, the faster engineers build structures, the faster Drop Ships are
repaired and refueled, and the faster new units are churned out from the Academy and
healed in the Hospital.
4. Controlling Battle Zones increases the player's unit cap. An overlay option will show the
player how many more possible units they will gain by controlling a certain Battle Zone.
Amounts will vary.
Unit Battles
Battle dynamics are simple, since the player is not in direct control: whoever has more units wins,
however fuzziness and battle-length allows for close-odds battles to tip either way. For example,
a 25 vs. 5 battle will definitely result in a victory for the greater army, and that victory will come
about quicker. A 20 vs. 10 battle will also result in victory for the greater army, however since the
odds are closer the battle will take longer to complete and there may be a chance the smaller
army will get reinforced before their numbers dwindle too much. In a 5 vs. 5 battle or even a 5 vs,
7 battle, victory could go to either side.
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Fig. 3 – Shortest Patrol route from one Airbase to another
Battle Control
So how does a player control his units on the ground when he's off flying his Drop Ship on the
other side of the map? Units have predictable behavior and when in need of direction, will radio in
for instructions. These requests will queue up in a UI element for the player to see and be
handled one at a time and respond via numeric keystrokes.
Unit Patrolling
When not assigned to secure a Drop Zone, units deployed in a Drop Zone will spread out, but
stay within the Drop Zone until they are set to Patrol. Players can fill a Drop Zone with units by
making several trips, and clear them to Patrol all at once, or set them on Patrol immediately after
unloading them. If the Battle Zone is not controlled, units will Patrol from one end of the Battle
Zone to the other and secure the second Drop Zone. If the Battle Zone is controlled, units will
Patrol towards the enemy Airbase. While on Patrol, they will attack any ground emplacements
and enemy units they encounter on their way to the opposite Drop Zone or the enemy Airbase.
Radio Contact
There are several reasons why a player's units will radio in for instructions. When instructions are
radioed in, they will include the type of contact (discussed below), the Battle Zone ID (displayed
on the mini map) and the number troops involved (this does not apply to all contacts). This data
will also be displayed on the HUD if the player accepts the contact.
Retreat
If units are vastly outnumbered, whether from the start of the battle or after the enemy reinforced,
they will radio in and ask whether to Retreat to the nearest Drop Zone for pickup, or hold their
position and await reinforcements (which the player does not have to provide). Retreating troops
suffer only half damage, but deliver only half as well.
Med-Evac
If units are no longer under fire, the severely wounded will request a Med-Evac from the nearest
Drop Zone. This request, if the player accepts it, will be canceled if the units come under fire
again on their way to the nearest Drop Zone. The level of health at which units call for a MedEvac can be set at the Hospital in the player's Airbase.
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Advance
When units automatically secure a second Drop Zone and thus a Battle Zone, they will radio in a
request to advance towards the enemy Airbase, if possible.
Build Structure
Engineers deployed in a Battle Zone will immediately move towards the nearest Build Pad and
upon reaching it, radio in and ask the player what structure they would like constructed.
Engineer Evac
Once all the Build Pads in a Battle Zone are used, the Engineers will move to the closest Drop
Zone and radio in for pickup.
In addition to units radioing in, the player can type in the Battle Zone ID and radio the units on
Patrol in that Battle Zone to muster at the nearest Drop Zone for pickup.
Ground Structures
In addition to units, the player can build ground emplacements to help fight both ground-to-ground
battles and ground-to-air battles.
Build Pads
Not every Battle Zone has to contain Build Pads, and there is also no limit to how many Build
Pads a Battle Zone can contain. Engineers are required to construct anything on a Build Pad, and
even if there is more than one Engineer, they can only work on one Build Pad at a time, although
a greater number of Engineers decreases build time.
Structures – Ground-to-Air
AAA
Anti-Aircraft Artillery is less damaging, but more effective at deterring Drop Ships thanks to its fast
rate of fire and fast tracking ability.
SAM
Surface to Air Missile emplacements can pack a deadly punch if they manage to lock onto a Drop
Ship. Players that fly within range of a SAM site will see a targeting cursor attempt to lock onto
their ship (along with audio cues). By flying out of range or avoiding the cursor they can avoid a
missile launch. If the emplacement locks on, the missile will launch and the player will have to fly
out of range of the SAM site to lose the missile lock, while avoiding the missile itself.
Structures – Ground-to-Ground
Bunker
The Bunker is a highly-fortified ground structure that is not susceptible to air attacks. It can house
four (4) units who are protected until the Bunker is destroyed by ground unit fire.
.50 cal
The .50 caliber machine gun emplacement is devastating to ground units thanks to its long range,
but highly susceptible to air attacks from gun port-manned Drop Ships.
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Structures – Support
Refueling Depot
If the player does not wish to travel back to their base for a refuel, they can land at a Refueling
Depot. The downside is that they cannot trade Drop Ships nor load any troops while doing so.
Medical Unit
Ground units in need of a Med-Evac can instead seek out the refuge of a Medical Unit within their
Battle Zone. Medical Units are set to accept and discharge units based on the values set at the
Hospital back on the Airbase.
End Game
Once a player's Airbase is overrun, or a player runs out of Drop Ships, the game is over and the
remaining player is the victor.
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