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Left 4 Infestation

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Level 2
Jun 23, 2011
The purpose of this thread is to garner interest, act as a form of progress report, and as a way to demonstrate my growth as a SC2 Map and Scenario designer. Also, if I ever need help, or if anyone has any suggestions, then it can all show up in this thread to be discussed.

Left 4 Infestation
A four player strategy survival and escape map.

The Premise
Jim Raynor sides with Dr.Hanson and fights off the Prottoss that wanted to cleanse the planet of Haven clean of infected refugees. As it turns out, Hanson infested herself and her colonists, and was only using Raynor to save her little hive from everyone else. Now, with the Protoss beaten back, out of range from Kerrigan's influence, and away from the prying eyes of other Terrans, Hanson is free to complete her vile project. From her laboratory in the capital city of Haven, she unleashes the full effects of her infestation research, and begins turning the colony into her own private hive of human-turned-zerg.

The Situation
Despite the everyone's best efforts to contain the Infested, they've escaped their facility of origin, broken out of the security pen, and have been running amok for who knows how long. You are the leader of one of four containment teams trapped in the city.

But you're not going to give up that easily. Rally your men, recruit survivors, and scavenge the city to beat back the infested. You're going to survive.

Player Rules - Overview
The game is designed for 1 to 4 human players controlling units of the Terran race. There are major differences between this map's tech tree and the tech trees of the campaign or multi-player maps. The only structures that can be built are defensive structures, such as bunker and turrets. Unit producing and researching structures are scattered throughout the map, and must be found.

Creating units doesn't cost minerals or vespean gas, only room in the population limit. Every units requires only 1 population point. Each player's population limits starts at 10, and increases with every civilian rescued. When a unit under their control dies, their population limits decreases by 1.

Each player starts with one Command Center, four Marines, an SCV, three Medics and two Fire Bats.

Productive Structures Under Player Control
Most structures are not initially under player control and begin infested. Infested buildings produce all sorts of units for the computer player, in a similar manner to the infested colonists of the Wings of Liberty Campaign mission Out Break. Players gain control of infested structures by sending in a Fire Bat to clean it out. Then a random number of civilians are released from it, which must be escorted by to the player's Command Center to be officially rescued. Some cleansed buildings also create units for the player to take control of.

A cleansed building can be re-infested by the computer player, which will be explained later. All of the Productive Structures do not take damage from the Terran or Infested Terran/Zerg units, as the factions find them too valuable to remove.

The Civilian Structure, the most common type of structure found throughout the map, using the models for the infestable colonist huts and things from the campaign, as well as the abandoned buildings and structures from the Korhal tile set. Cleansing this structure for the first time frees a number of civilians, and allows an SCV to enter and collect salvage from it (which is how resources are gained). Civilians can be rescued only once from a civilian building, so re-cleansing a re-infested building doesn't reset the number of civilians to be rescued. The number of resources within are also limited in the same way, they just take longer to acquire.

The Command Center allows the player to equip civilians with either an SCV suit, or a Marine suit and riffle, creating those respective units. The Command Center has it's flight system damaged, so it can't lift off. However, it can be upgraded to a Planetary Fortress if it's controlling player has and Engineering Bay. Unlike the Planetary Fortress upgrade from the campaign or standard multi-player, these cannons have a huge range to provide fire support from a great distance.

Cleansing a Barracks possibly frees a few civilians, and creates a few Marines, Fired Bats and/or Medics. The Barracks allows a player to arm civilians with medical gear or heavy armor and flame throwers, essentially creating the Medic and Fire Bat units there. Just like the Command Center, the Barracks cannot lift off.

Every Barracks has a Tech Lab attached, which has all the research options for Marines, Medics and Fire Bats. The Tech Lab also has research options for the Marauder and Reaper unit, but they are unavailable if the player doesn't control and Armory.

Cleansing an Armory possibly frees a few civilians, and creates a few Marines, Marauders and/or Reapers. The Armory also allows a player to arm civilians with the equipment to create Marauders and Reapers, and unlocks the research options for those units at the Tech Lab attached to a Barracks.
  • Upgrade Weapons - This upgrade slightly improves the damage dealt by units the player controls. It can be researched up to 3 times.
  • Upgrade Batteries - This upgrade slightly improves the damage dealt by defensive structures the player controls. It can be researched up to 3 times.
  • Upgrade Armor - This upgrade slightly improves the damage dealt by everything the player controls. It can be researched up to 3 times.

Cleansing an Engineering Bay possibly frees a few civilians, and creates a few SCVs and/or Marines. The Engineering Bay has research options for each of the defensive structures as well as for the SCVs, and the Command Center.
  • Badurium Building Plating - Buying this upgrade increases the life armor of all the defensive structures the player controls by 3. Costs 150 Minerals and 50 Gas.
  • Fire-Suppression System - This upgrade is like the one from the single player campaign. Researching it causes damaged defensive structures the player controls to heal up to 50% instead of burning down. Costs 50 minerals and 150 gas to research.

Defensive Structures
Defensive structures have to be built by an SCV. They can all also be salvaged for a full refund. Defensive structures cannot be infested, though there are Infested Bunkers that can be cleansed, and the computer opponent destroys them.

The Bunker functions as normal, being a little place for a few troops to take cover in and fire out of.
  • Shrike Turret - The same upgrade from the campaign is available at the Engineering Bay, which puts a gun turret on the top of the bunker. Costs 50 Minerals, 50 Gas.
  • Fortified Bunker - The same upgarde from the campaign that granted the Bunker an additional 150 health is also available. Research it at the Engineering Bay for 100 Minerals.
  • Neosteel Bunker - Guess what? Upgrading the bunker from only holding four units to six is also available, an option found in the Engineering Bay. 100 Minerals.
  • Projectile Accelerator - Yep. A player can research that too, if they control an Engineering Bay. 50 Minerals, 50 Gas.

The Perdition Turret is also available for construction if a player controls a Barracks. Just like in the campaign, it hides in the ground until an enemy is near, then pops up and unleashes fiery justice, dealing a bit of extra damage to Light units. Costs 100 Minerals to construct.
  • High-pressure Flamer - Increases the Perdition Turret's Attack Range by 3. Research at the Engineering Bay. 50 Minerals, 50 gas.
  • Thermite Filaments - Stolen from the Helion's campaign upgrade, this upgrade increases the Perdition Turret's damage to Light Armor by 10 (All of the Infested Colonist's units have light armor). Costs 100 Minerals, 100 Gas to research this upgrade at the Engineering Bay.

The Missile Turret is a bit different from the Missile Turret from the campaign and standard multi-player. It isn't a detector, but it can attack ground units. Cost 100 minerals to build, and deals extra damage to armored units.
  • Hellstorm Batteries - The Missile Turrent's only upgrade, and is the same one from the campaign with this name, which changes it's attack from only affecting a single target to damaging everything in an large area. Costs 100 minerals and 150 gas to research, at the Engineering Bay.

The Psi-Disrupter is available to build if the player controls and Engineering Bay. It functions just like the one from the campaign, but costs a whopping 300 gas to build, in a addition to 100 minerals.

Terran Units
The various units to control will have the same stats as the regular units from the Wings of Liberty campaign, and multiplayer. Some differences and the upgrades:
  • All units will only take up a single population point, and permanently reduce the maximum when killed. This represents the limited pool of warriors to recruit from the cut off city. On the plus side, units are free to create, if the population limit can support them.
  • Marines will have 55 health, starting off with their Combat Shield upgrade for free.
  • Stim Packs - Researched at the Tech Lab for 100 minerals and 100 Gas, this unlocks the ability for the Marines, Marauders and Fire Bats. The ability increases their movement and attack speed at the cost of health as normal.
  • U-223 Shells - Back from Starcraft 1, this upgrade increases the Marine's attack range by 2. Research for 100 minerals and 100 gas at the Tech lab.
  • Juggernaut Plating - Just like the campaign upgrade, increase a Fire Bat's armor by 2. Costs 100 minerals to research it at the Tech Lab.
  • Incinerator Gauntlets - Just like the campaign upgrade, increases a Fire Bat's area of effect for the one time cost of 50 Minerals and 100 gas, payed at the Tech Lab.
  • Concussive Shells - Just like the campaign upgrade, give the Marauder's attack a slowing affect in a blast radius around its target. 50 minerals, 100 gas, Tech Lab.
  • Kinetic Foam - For 100 minerals, this upgrade can be researched at the Tech Lab. Just like in the campaign, it increases a Marauder's health by 25.
  • Stabilizer Medpacks - Just like the campaign research option, this ability greatly increases the rate at which a medic heals a friendly unit, and reduces the energy cost to do so. 100 minerals, 100 gas, at the Tech Lab.
  • U-238 Rounds- Increases the Reaper's attack range by 1 and damage to light armor by 3. 100 Minerals, 100 gas, Tech Lab.

Scenario End Conditions
Simply put, a player loses when their population reaches zero in a bad manner. This automatically happens when they have no units and their Command Center/Planetary Fortress gets infested, or when they have trained every citizen and had them all killed. Bad resource management, excessive defense or just poor risk assessment would usually be the culprit. Since the same number of Infested Colonists spawn regardless of how many players there are, playing alone can make the scenario more difficult.

In terms of Victory Conditions, the first is the team victory, in which the players manage to cleanse all of the city's buildings and kill all the infested colonists. This is a very difficult task, as not only does every building spawn more and more Infested Colonists, Infested Marines, and Aberrations over time, by these units don't burst into flames during the day. Also, the streets are filled with hoards of the things just sitting around and waiting for something to grab their attention. Dr.Hanson, calling herself 'The Infested Queen', also gets more an more powerful as time goes by, and killing her can be impractical if done later as opposed to sooner.

The second possible Victory Condition is a little easier to accomplish, but there are a couple of issues with it. Scattered across the city are entrances to underground subway stations with a locked gate. A player can order an SCV to unlock these subway stations. If two or more are unlocked, then they'll be connected, allowing the players to send units to board the train hidden underground and go to the next station. Unfortunately, the Infested Colonists have wandered into the subway stations, and unlocking one frees a whole bunch. Additionally, Infested Colonists can also get into the subway stations, board the train, and come out at another station, gaining more mobility and unpredictability.

When all of the stations are unlocked, a timer will begin. Every player's population will drop to whatever it is being used currently, and a number colonists equal to the dropped amount will spawn from their Commander Center/Planetary Fortress and head to the nearest subway station entrance. The Players will have to send their own units to the stations as well, which will reduce their current and maximum population even further. If a player's population has been reduced to 0 from this event, then they win the scenario. At the end of the count-down timer, a train will be seen leaving from the Train Station doodad from the Tarsonis Map, representing all of the escaping people. Any player that still has units left outside of the subway stations when the timer ends will be left behind to continue cleansing the city on their own, losing any units they had inside.

Infested Colonists and the Map
The melee units the Infested Colonists and Aberrations, as well as the Infested Marines, all from the campaign appear in this scenario. Just like the Outbreak Mission, the Map cycles through night and day at regular intervals. During the day, the Infested don't start anything, though they will continue doing anything they started doing before hand. At night, infested buildings will spawn the various zombie like units, at first in small numbers, then with greater frequency. A few of the spawned units will just wander around aimlessly and fill the city streets, but most will be sent to attack a nearby player. Unlike the Out Break mission, these units do not burst into flames sat day break, and units sent to a player from a great distance will continue shambling forth as time goes by.

With each passing night, the ferocity of the Infested's attacks increases. Their numbers increase, and eventually, so does their health, armor and damage.

The core of the infestation is the Laboratory that Dr.Hanson started this all from. Every night, Infestors, a real Zerg unit, will spawn from it and begin wandering the city. If they come across an un-infested and unguarded building, they will go inside of it and infest it, taking control of it away from what ever player happened to abandon it.

Hanson herself comes out of the building at night, though a player can cleanse the Laboratory to force her out during the day. She's a very powerful hero unit, and becomes even more so with each passing night. After many nights, her research will be completed, and she'll encase herself in a cocoon. She'll be defenseless in this state, being immobile and having tons health and armor, but when she emerges, she'll have mutated into full realized Zerg Leader. A couple drones will also emerge with her, which will move to the nearby park and start mutating into hatcheries.

The Computer AI will then start working up the Zerg tech tree and attacking the players with proper Zerg units until it crushes them.

My mother taught me to thoroughly plan everything. That way I know what I'm doing, and have mini-goals to achieve on the way,.

  1. Map Creation
    • Tile set - Done
    • Roads and City Blocks - Done
    • Traffic and Street Lights - Done
    • Start Locations - Done
    • Important Points
    • Pathing
    • Populate with Civilian Buildings
    • Populate with Controllable Structures
    • Populate with Passive Hoards
    • Populate with Hanson's Hive
    • Populate with Doodads and Features
  2. Programing
    • Figure out how to do it...
  3. Player Rules
  4. Computer Rule
  5. Cinematics
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Level 27
Jul 6, 2008
The concept is very intresting and sounds promising...

Also I like the storyline idea, I mean it's actually so awesome I wish this would be the part of original SC2 storyline.

I hope that non-civilians will be requalifyable, too. Like shall we say you need SCVs but got no civilians, so you can send some marines to become SCVs, and SCVs can be turned into marines, too. Well I think you got the point...
Level 2
Jun 23, 2011
I hope that non-civilians will be requalifyable, too. Like shall we say you need SCVs but got no civilians, so you can send some marines to become SCVs, and SCVs can be turned into marines, too. Well I think you got the point...

Now that is an good idea. I'm certain I can implement it... maybe a button on the Command Center would work, since that's were all the civilians go to hang out.
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Level 2
Jun 23, 2011
OK. I think I've figured out what I have to do to make the various buildings to work the way I want them to. For each productive structure type, there's two data sets. The Player Controlled version, and then the Infested version.

The Player Controlled structures, they have all the buttons and unit creation rules associated with them. Then I add ability to the Infester unit that it uses on the infestable buildings, going inside like the old SC1 Zerg Queen did, which triggers a Morph on the building to the Infested version.

The Infested buildings all share same abilities, in that they spawn Infested Colonists and things; a few to linger around, and some to go after a player's units. I then give the Fire Bat unit a Cleanse ability that does the same thing as the Infester unit, where the Fire Bat goes right up to the building, disappears for a second, then reappears and the building has Morphed into the cleansed, Player Controlled Version.


In other news, I decided to have Player Controlled Civilian structures work like Refineries, in that a player orders an SCV to gather minerals from it. The worker goes up to it, disappears for a second, then reappears carrying a load of salvage. The questions I have are:
  • Would it be better to have the building assign what the SCV comes out with, and have buildings with a set amount of Minerals and Vespean?
  • Or would it be better to have the salvage be anything until it reaches the command center, and then the resources gained be random/equal/specific ratio?

Should I increase amount of types of infested colonists? Wouldn't it make the computer AI a more interesting opponent if it had access to Infested Marauders, Fire Bats and Reapers? Infested Medics feel thematically inappropriate, but what about classic SC1 Infested Terrans, the super fast suicide bomber? Or even infested Snipers? (effectively infested ghosts without nukes or cloaking... maybe cloaking)
Level 4
Jun 18, 2011
Nice, so basically it would be check point battles using starcraft in a Left 4 dead setting.

Basically any infested units would mutate into more zerg like beings. Having fire bats become the bombers, marines become shooters, medics become into healing/support, Maruders would be heavy shooters, reapers into jumping shooters, ghost/spectre into command units (Since kerri was a ghost) and have colonist become offensive workers.

Basically any thing that shoots will have a modified attack damage, like acid splash damage or something similar that is very zerg.
Level 2
Jun 23, 2011

Stuff done: Got most of the action cards for the player's stuff done. Went through and made all the upgrades and researches right, as well as the unit requirments. Moved the building abilities around so that the buildings made the right units, and the armory could set rally points.

I discovered what the difference is between a 'use/has ability' button and 'research ability' button. Making those buttons is on the list.

For some reason, the tech lab won't attach to the barracks, despite the fact that I left the Addons ability of the barracks on it.

The 'Upgrade Terran Infantry Weapons Level 1' requires that 'Terran Infantry Weapons Level 1' be researched already, despite the fact that the requirement doesn't say that.

Also, 'Upgrade Terran Building Plating Level 1' can be queued endlessly, though the increase is only effective once. The Lvl1 button also blocks the Lvl2 button, so 'Upgrade Terran Building Plating Level 2' can't be queued. The same thing happens with the fortified bunker upgrade. Another requirement glitch.

Up Next:
Figure out how to get the civilian buildings to function the way I want them to, at the very least in terms of resource gathering.

Figure out how to get the population limit to behave the way I want it to.

Figure out how to get the cleanse and infest abilities to work the way I want them to.

Also, some terran buildings don't have an infested equivalent, such as the Korhal doodad buildings. I'm going to have to figure out a way to make one.
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