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About The Level

  • Research project utilizing Self-Determination Theory to create a level in Call of Duty 4

  • Capture a Middle Eastern city with your allied marines

  • Take side paths down streets and through buildings in any order you want

Project Goals

  • Build an epic battle, with large numbers of AI on both sides

  • Create a free-flowing layout that allowed players to play how they wanted to

  • Script events in the world to give the feeling that the battle is much larger

Project Info

  • Project Duration: 8 Months

  • Team Size: 1 Developer

  • Game: Call of Duty 4: Modern Warfare

  • Tools Used: Radiant Editor, Sublime (GSC), Photoshop, Premier

Major Influences

medalofhonorairborne_box.jpg

  • Uses Hub and Spoke design to create a chaotic battlefield

  • AI allies and enemies spawn and move to direct the player to incomplete objectives

  • Reuses central areas for later objectives

  • Large battles where you can support multiple allied groups

  • Gain support from the groups that you help depending on their type

  • Effects and voice lines communicate the larger scale of battle

Level Walkthrough

Scripting a Large Battle

Moving the AI

To make a large battle, you need a lot of participants. One major challenge of creating this level was making sure that the AI moved through the space realistically. They have to:

 

  • Be where the player is and realistically help or hinder them

  • Be able to anticipate where the player needs to go to show possible paths

  • AI of allies and enemies need to be able to react to each other

 

This was a challenge in itself, but putting this into a non-linear design greatly increased the difficulty. To overcome this problem, I made use of the built-in colored node system and the flag system. By flagging variables, I could tell the game where the player was at any given point and use that value to change the active color of my allies to bring them to the right place. 

Overview and progression of the level. Sections are broken down by color to represent different areas of AI flow

Checking flags to determine what units to spawn and what color to use

Using the set spawners and colors to spawn AI and play sound effects

Overview map. Shows how AI move based on objectives completed

Creating the Feeling of Scale

One of my major goals was to make this battle feel like it was larger than just what was around the player. Implementing multiple paths was one way that I approached this problem, but it wasn't the only way:

 

  • Helicopters flying around at key points (including some getting shot down)

  • Using effects in the distance to show that there are things happening elsewhere

  • Voice lines can convey more is happening without anything being seen

 

All of these different aspects work together to give the player an illusion of scale without the scope of the level becoming too much for them to handle. 

Directing the player to multiple paths

Showing the Player What to Do

Conveying Choice

The design called for a non-linear battle that presented options for the player to approach it in any way they wanted to. Just creating the choices wasn't enough. Even though every tester approached the level differently and took different paths, they didn't realize they had the option. Without knowing those choices existed, players saw the level as linear which defeated the entire impact of it being non-linear. 

 

To combat this, I focused on the major choice point that occurs early in the level. The goal was to prime players early that there are choices to be made. I used:

  • AI movement - Enemies retreated along both choice paths and allied forces chased after them.

  • Combat - Tester feedback showed that when they lost track of where to go, sounds of combat brought them to where they should go, so I made sure that every path had sounds of combat with some visibility to fighting allies

  • Voice lines -  Dialogue is a powerful tool where I can tell players directly what is going on and what the options are. 

  • Side Paths - Giving players small choices to go around an enemy position or go to a sniper perch gives them the freedom and desire to explore and find these alternate ways to accomplish their objectives. 

Giving the player side paths based on playstyle

AI fight along different paths

Conveying Objectives

Just giving a player a text objective and a waypoint isn't enough to get players engaged in what they're doing, a lot more has to go into conveying what that objective is and how to accomplish it. Two examples from this level that needed conveying are planting C4 on an anti-aircraft gun and defending a plaza. For both, I used a lot of the same techniques as I did above in conveying choice, but this time to specifically show players what to do. 

Defending the Plaza

While I was still able to use methods like AI movement and voice lines to convey this objective, I found that players typically defeated a wave and then would wander off. I took that feedback and added features to contain the player more:

 

  • Scripted Effects - I added smoke to cover the exits from the plaza to create a mental block of those areas. I also gave the enemies vehicles to come in so that they could partially block the road off physically. 

  • Machine Gun Turret - Having an emplaced weapon makes the player feel more powerful when defending against large waves, but it also encourages them to stay more stationary. 

  • Air Strike - To reward players for destroying the enemy anti-aircraft guns, I gave them the ability to call in airstrikes. This gives the player a powerful ability that they are able to tie directly to accomplished objectives. 

Destroying an AA Gun

Using animations, AI movement and glowing objects were key to conveying this objective. There are two AA guns and you can see an ally go over to one of them and start placing a charge on it, while they tell you to do the same. This tells players what to do and shows them how to do it. 

 

Call of Duty's built-in conveyance was a huge help too. They use glowing objects to indicate interactable objects. Following their convention made it significantly easier for players to understand.

Defending the Plaza with a turret

Calling an Airstrike

Destroying the AA

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