(CNN) -- For all of its expected action and drama, the new "Halo 4" boils down to an essential question: Are its central characters humans, machines or something in between?
The answer may still be unclear by the time you're done playing this fantastic game.
This edition of the hugely popular "Halo" franchise was developed by 343 Industries, which took over after Bungie Studios, creators of the first four games, split from Microsoft. To its credit, 343 Industries has retained the intense first-person shooter action "Halo" fans are used to but upped the emotional interplay between the iconic Master Chief and his artificial-intelligence companion, Cortana.
The action begins with Master Chief in cryosleep and Cortana starting to undergo rampancy, a condition for older AIs in which they actually think themselves to death. At one point, Cortana likens it to having 1,000 arguments with herself, but she tries desperately to hang on to her sanity to help the Chief, her human ally.
The connection between these two characters makes this campaign really special. From the opening scene with Catherine Halsey, the creator of the story's super-soldier program, to its climax, the tension between humans and machines runs throughout the story.
Cortana seems more emotive than before -- a welcome addition to the character. Master Chief retains his detached, no-nonsense soldier persona for most of the campaign, but there are moments you want his helmet to come off so you can see the facial expressions you sense he's making.
"Halo 4" hooked me emotionally before I realized it. Some scenes made me feel waves of despair or elation before I recognized I was mirroring the emotions in the game -- truly a sign of an immersive experience.
The graphics of "Halo 4" are outstanding in their detailed depictions of characters and background environments. Whether foliage for a jungle setting or the individualized movement of little bits of wreckage, each scene is treated with careful attention to the smallest element.
Characters look like live-action actors, and their movements and emotions have a realistic, almost filmlike quality. This technique has been used in other games, but "Halo 4" raises the bar for others to emulate.
The voice acting and dialogue are fantastic and help pull you into the story. You'll quickly hate some characters based merely on the inflection in their voice. (You may even wish you could shoot them in the face -- I know I did -- but you can't.)
The game introduces a new character from the recent "Halo" Web series, and I sometimes wondered if I was missing inside jokes from the related "Halo" books. But knowing the entire "Halo" universe isn't a prerequisite to enjoying this game.
There are eight missions in the single-player campaign, with plenty of weapons and vehicles from which to choose. Combat in the game seemed more strategic than the straightforward, hard-charging style we've come to know from previous "Halo" titles. For example, using the armor's jump-pack accessory allows players to leap up to hidden spots and pick off enemies. And other armor abilities allow Master Chief to create a floating turret, which I found great for thinning out a battlefield before wading in.
Don't worry, fans -- the big action sequences are still there. "Halo 4's" epic fight sequences require players to confront waves of enemies in one mission, then pick off bad guys one by one in another. And of course, co-op and online multiplayer action is available if you want to include a friend or try your luck against an opponent.
Despite all the mayhem, what stood out for me about "Halo 4" was the story. The new developers made an effort to delve into the characters we've known over the years and morph them into something fresh.
The "man or machine" question becomes more prevalent as the game progresses, and I found myself looking at different missions and scenes through that lens. Is Cortana more human as her mind begins to splinter? Does John-117, the solder we know as Master Chief, become a robotic killing machine?
Or have both influenced each other so much that the differences we expect between the two become mixed, creating a symbiotic relationship that only becomes evident when one side lets down the other?
During one tense scene, Master Chief tells Cortana, "I was supposed to protect you." She replies, "We were supposed to protect each other."
The deepening interactions between these two main characters enhance the narrative and make "Halo 4" a wonderful new addition to a beloved franchise -- and the best "Halo" campaign so far. It keeps me wanting to play over and over again.
"Halo 4" is available now throughout most of the world and will be available Thursday in Japan as an Xbox 360 exclusive title. It is rated M for mature due to blood and violence. Online interactions are not rated. This review was done with a provided limited edition copy and is solely focused on the single-player campaign.