At a GDC 2013 panel today, Scott Warner, Halo 4 project lead designer, discussed the iterative process and key moments in creating the new Promethean enemies for developer 343 Industries' first foray into the Halo universe.

The broad talk covered the Promethean's inception to what you fought against in the shopped game. Warner said that his intent was to give insight into the challenges and decisions the studio had to make and to help developers learn for their own games.

Warner stressed that, although he was presenting, the Prometheans are a result of the works of artists, engineers, sound designers and more over the three and a half years of Halo 4's development.

Prometheans were a result, in part, with "player fatigue" dealing with the series' constant Covenant enemies.

"We knew that, matter what we do, we have to provide players with a brand new experience," he said.

Creating new enemies was a good way to invest the studio's time and create "another 30 seconds of fun," an allusion to Bungie's not-so-secret recipe for success.

The studio took design lessons from "the legacy of the franchise" and build upon the foundation that Bungie had established. This included the axiom that "every enemy race is unique," both visually and in terms of gameplay mechanics. Because "Halo is a sandbox game (as opposites to a highly scripted narrative)," 343 wanted to ensure that "enemies support experimentation." The developer also carried forward the "leader/minion" concept, in which enemies have squad leaders and a boss. That allows the combat scenarios to have a clear flow and mirrors human squad makeup, he said.

Building upon these systems, 343 also adhered to the "Halo encounter" template, which 343 reverse engineered by studying Bungie's Halo games. Warner characterized encounters that adhered to a flow of "plan, take them by surprise, beat them back, break them up, mop them up, repeat."

The approach to difficulty is "opaque" most of what chaining isn't the character, but "they become a little bit smarter, they become a little bit faster." Their weapons are better, fire faster, they can pilot vehicles.

343 also used the existing content creation tools pioneered at Bungie and building upon that. After Halo 4, he said, 343 would decide whether or not to revamp the system.

Warner characterized those as foundations of the game. Prometheans were the studio's attempt to build upon the existing Halo canon, particularly with regards to the backstory. The animated series Voltron and the T-1000 from Terminator 2: Judgment Day were early inspirations for the shapeshifting Prometheans.

Creating a race that could be completely adaptable started to influence other parts of the game like the environment, he said.

The early goals were to create something familiar, yet alien.

"This is kind of a great lesson from Star Wars," he said.

Enemies needed to be cooperative and they need to adapt their form to the environment.

Familiar, yet alien. Cooperative and adaptable.

The first enemy 343 created was the Knight (pictured above), a humanoid biped. 343 believed that would understand the new character based on the design. The dog-like Crawler came next. It began as a biped, which wasn't "super interesting" and eventually became animalistic. Finally came the Watcher, which "would completely change up the combat encounter through abilities like shields and resurrection."

343 also created three more characters that didn't make the game, but which Warner said 343 would "probably" get to at some point.

During the prototyping phase, 343 experimented with many possible moves that enemies might be able to make. He shoed an early video that he characterized as "pretty much the very, very, very first thing" the studio created. In the video, the player fought a Brute that was being protected by a Watcher deploying a drop shield.

A video showing the "first fully-formed gameplay prototype for Halo 4" dating from about May 2010 in which an early Knight prototype transformed to into a ball reminiscent of Metroid. 343 learned that it needed to "reduce the scope" of what it was up to because the interrelating systems were difficult to program to work together.

That's when he studio decided to pare back the original six Promethean enemy classes to the three that shipped with Halo 4. 343 also cut many of the prototyped abilities, which eventually began to make the enemies "a little bit of a Swiss Army Knife." It also helped that the studio had begun to flesh out the Promethean backstory, which provided natural boundaries that exceeded the early ball form.

How does 343 feel about the enemies it created, and what could have made the process better? Warner pointed to several areas that could have improved the process, including better early communication among the team, the absence of a "high-level vision for too long."

Perhaps most importantly, Warner said that the Prometheans were "devoid of emotion," which broke the Halo formula that communicated a relationship between the characters.

"They tend to not show a lot of emotion or communicate that very well," he said.

It's a problem that the studio hopes to fix in the future, he said.

For more on Halo 4 at GDC, be sure to read Polygon's coverage of a talk from earlier this week about creating the live-action Halo 4: Forward Unto Dawn webseries on a "threadbare" budget.