When people think of game A.I., they tend to imagine something out of science fiction—Skynet or Agent Smith—with millions of lines of code written by a mad-scientist programmer in a dimly lit basement. The truth is that game A.I. is an intensely collaborative effort. The actors you see onscreen are the final product of years of work by animators, character modelers, sound engineers, programmers, and level designers. As the enemy A.I. programmer, my work was more concerned with developing a framework for creating interesting gameplay than it was about evolving hyper-intelligent programs. Without all of those other contributors (especially animators and level designers), the A.I. wouldn’t exist.
There are as many ways to write enemy A.I. as there are games on the market. Every programmer has a different style, and every game has its own unique set opportunities and challenges. Great A.I. isn’t necessarily the smartest A.I., but rather the A.I. that best supports the core gameplay and creates exciting, memorable moments. As a squad-based, gritty, militaristic first-person shooter (FPS) set in the Star Wars universe, we knew that we needed A.I. that was diverse, believable, and flexible.
Inspired by the wildly imaginative creatures in the classic Star Wars movies, we wanted a cast of A.I. characters that was as diverse as the Star Wars universe would allow. Unlike so many FPS titles, where the only difference between soldiers is the color of their pants, we created A.I. that had genuinely unique behaviors, strategies, and personalities. The final version of Star Wars Republic Commando™ has more than a dozen non-player characters (NPCs), including armored droids and agile insect warriors, flying soldiers and crawling drones, intelligent humanoid mercenaries and lumbering robotic tanks, each of whom have their own custom personality, weapons, and tactics.
We wanted A.I. that felt human, A.I. that was interesting and believable. Inspired by games like Halo andHalf-Life, we knew that we needed A.I. that was intelligent, but fallible … A.I. that the player could learn from but eventually outsmart. Our A.I. never cheats (well, almost never ;). Like a human, A.I. characters make their decisions based only on what they have seen and heard.
In a game as complex as Republic Commando and with the amount of freedom given to the player, it’s critical that the A.I. be able to react to the widest possible range of player actions. We knew that we would need A.I. that could improvise in response to the player’s decisions, unlike the scripted, sometimes-brittle A.I. in other popular shooters. While we do use some scripting to create dramatic, cinematic moments, the vast majority of our combat is completely player-driven.
Even with these clear goals in mind, developing the enemies forRepublic Commando was hardly without its surprises. Something we learned the hard way during the development ofRepublic Commando was that FPS games are, well, all about shooting things. That may sound obvious, but the implications aren’t (or at least they weren’t for us). The lesson for us was that hit reactions, weapon effects, and fantastic looking death animations and ragdoll affects are just as important to creating the impression of fun and interesting A.I. as intelligence. After some pretty rough feedback during one of our focus group sessions, we completely re-wrote the entire weapon effects, hit reactions, and death physics system. The final product is something we are very proud of, but it was something that we had to react to “on the fly” under already tight time constraints.
Developing the enemies for Republic Commando has been an enormously rewarding experience. We set high standards, worked hard to achieve them, and did our best to improve the game in response to feedback from our peers and potential customers. We’ve delivered a diverse array of believable, flexible, and intelligent enemies that are as fun to fight as they are to kill.
It’s been a blast bringing the Republic Commando enemies to life. We hope that you have as much fun fighting them as we've had making them.
