Yep, rather than always forcing you down a scripted hallway, where funhouse Nazis will pop up on cue for you to shoot, the new game is all about increased player freedom and choice during missions. Call Of Duty 2 won't be completely unscripted, but you can now accomplish objectives in different orders and take a unique path through a level.
"This gives you strategic choices for which active objective to complete, and the opportunity to use actual military tactics like outflanking, and fire and manoeuvre to eliminate the enemy," states lead designer Zied Rieke. Call Of Duty 2, therefore, instantly offers you increased replay value. You can now return to a favourite mission and attempt to complete it with, say, balls-out guns-blazing, rather than with a careful, considered strategy.
And there's more. "Rather than forcing you through each mission one at a time," adds Rieke, "when the player finishes a particular mission or 'vignette', we allow you to choose which of the characters' stories you'd like to continue next. You can follow a particular soldier's story through to completion, or alternatively, you can play chronologically across all the conflicts from 1941 to 1945."
Yet Infinity Ward was very aware that to produce its trademark intense battlefield experiences in large, mainly non-scripted levels, Call Of Duty 2 was going to need significantly revamped AI for both the friendly and enemy troops. "Squad behaviour in COD was pretty good, although enemies weren't quite up to scratch," says Zampella. "Now, on both sides, the AI has improved, and you can come at the enemy from different angles - although they'll now do the same to you. You need to watch for that - the enemy communicates with each other in the same way that you do with your squad. If you're flanking them, they'll communicate that to each other verbally, and shout it out - although you'll need to understand German to tell what they're saying! You won't be able to just sneak up on a guy unawares if there's a battle going on ten feet away."
Probably the best example of this in a recent shooter with wide-open levels, is the way the enemies react in Crytek's superb Far Cry, shouting to each other and calling in other units for help - but Zampella insists that the 'Battle Chatter' system in Call Of Duty 2 is even more sophisticated. Apparently, the AI on both sides (although you'll obviously only really be concerned with your own squad's voices) will call out over 700 different phrases that are context-sensitive to the level, such as, "Sniper, second-floor balcony!" or "Watch that guy over there!"
"These aren't scripted events - they're driven by the game's AI. It's very detailed and meant to mimic what real soldiers do in battle. That was one of the things our military advisors commented on from the first game - once the first shot is fired, the element of surprise is gone. Soldiers on the battlefield communicate constantly, whether it's "Hey, I'm reloading!" or "Cover me!" If you listen and pay attention to what they're saying, you'll get clues to what's going on around you. Of course, this is extremely important with non-linear gameplay - if you hear someone shout out "They're flanking us on the left!" then they're flanking you on the left!"
In Call Of Duty (and United Offensive), your AI squads would sometimes take the lead in firefights, but would never progress too far in front of you in a level - an element that has been retained for the sequel. "We don't want the friendly characters to finish the level for you, so there's a range where they'll advance. However, while they won't go miles ahead, we've tried not to make it feel like an imaginary line, where they don't react until you cross it," elaborates Zieke. So the team hasn't been tempted to include direct squad control? "Well, I'd say we've been tempted, but what people like about COD is that there's so much stuff going on all the time and it's so intense and exciting, that they don't have to deal with that level of tactics."