Butcher Bay has been augmented a little as well in terms of Gameplay, all of the changes from Dark Athena have been retroactively applied to the BB chapter and the sections from the PC version of the game have been added and revamped, as well as several areas from BB that were too confusing. There's a section that involved some hard to navigate sewers, these have been tightened up and now it's easier to get through, less frustration and a slower respawn rate to certain enemies.
Riddick also plays with the concept of Hub levels; in BB you have a large prison area and some interesting side missions. Dark Athena has something similar and allows you to return to the same place to learn more about what's going on. Many people would see this as padding, however, it's done so well in both games you very rarely feel that you're being made to replay the section again, just pass through it on the way to another rendezvous with the Athena crew and Riddick's Ulaks.
I'd mention more about the drones, but I am going to let you find that out for yourselves.
This all adds up to a highly polished Gameplay experience that still remains strong to this day, right up against the market leaders.Graphics
Rather than just take the game and port it from Xbox to Xbox360, Starbreeze have taken the game and rebuilt it from the ground up. There's no old textures that have been reused, no level design that has been revamped. They have rebuilt the game and it shows if you look at the comparisons between the old 2004 and the new. The prison's corridors are even more detailed, better lit and have far more character than they did in the previous iteration. The levels have a bigger feel to them and of course with the new lighting they can take advantage of better shadows and design than before.
It's not just the levels that have been remade; the models too have been given a brand new look. There are significant changes in many of the key characters, Hoxie (the Warden of Butcher Bay) has been given a more reactive face, the hands now have better articulation with their fingers and the various subtle differences to the models textures are echoed in their clothing as well. Hoxie is wearing a totally different costume in the 2004 game. Every model you can think of has been redone and retextured.Animations
Not content with remaking the graphics, Starbreeze have also redone the animations, they are more fluid this time around and take into account a wider array of combat moves in hand to hand. There is still the odd glitch where a stealth kill doesn't sometimes line up properly; it's not a game breaker though when you're having so much fun. There's also a greater degree of emotion to the character's faces as well as more motion to their bodies in general.Physics
Riddick always seemed a little physics light, not having as much boom as other games. This remains the case, though the reactive physics in combat are excellent and you can shove people around, knock them on their ass and in turn they can do the same to you. It makes the hand to hand very visceral and brutal. In gun combat a headshot will take a single foe down and it will take more shots to the body or limbs on many guards. The physics system seems a little more Hollywood for the firearms and people will often fly backwards flailing through the air - again who cares when you're having so much fun.