Halo 4

Cortana: Wake up, John! Chief!
Master Chief: I'm here.

Halo 4 continues the story of the Master Chief in the Halo franchise (actually the seventh official game, three others tell side-stories not involving MC). Drifting through space and in hibernation, the Master Chief is woken up by Cortana and they engage on a new adventure involving a previously unknown enemy. The second trilogy has been officially named "The Reclaimer Trilogy".

The first trailer for the game was shown at the end of Microsoft's E3 2011 press conference. It is stated for a Holiday 2012 release and is the second game not to be developed by Bungie Studios (the first being Ensemble Studios' Halo Wars), but 343 Industries who have taken the reins since Bungie finished their run with Halo: Reach.

The trailer can be viewed here. In the same vein as Halo 3's cinematic trailer, the guys at 343 have said that the events depicted likely won't happen that way in-game (although new elements like Master Chief's armor changing while he was supposedly in cryo were intended and will be explained... eventually).

343 Industries released a First Look showing off the new SPARTAN IV armor for multiplayer, the updated Battle Rifle, hints that the Big Bad will be even more threatening than the Halo rings, the new music score and a title sequence that strongly hints at a cybernetic Forerunner Big Bad. Microsoft has hinted in the release date announcement "Master Chief returns to confront his destiny and face an ancient evil that threatens the fate of the entire universe."

The game officially will be released on November 6, 2012, and will take place four years after the events of Halo 3.

Tropes used in Halo 4 include:

Abusive Precursors: The Forerunners, or at least their remaining tech, make their on-screen debut in the Halo series. Specifically, the default enemies are from the Forerunner warrior-caste called the Prometheans... or at least, their battle droids.
A.I. Is a Crapshoot: Cortana is getting to the stage at which she is in danger of going rampant, and that will be explored.

Cortana: I was put into service eight years ago. A Is deteriorate after seven years.

Call Back: The last thing Master Chief said to Cortana before going into cryogenic sleep in Halo 3 was "Wake me... when you need me." The Halo 4 trailer has Cortana repeatedly calling out, "Chief, I need you!"
Character Development: 343 Industries has confirmed that John-117 has changed psychologically during his long cryosleep. As seen in the E3 2012 gameplay trailer, he seems to be more willing to talk on missions and to care more about his fellow soldier, rather than simply doing a job stoically.
Female Gaze: One of the most cited changes to Chief's armor is the loss of its codpiece. Yeah, very uncomfortable for those who aren't into the view. Those that are probably found it quite acceptable. Frank O'Connor reports that was an issue with rendering in the initial trailer, and not an intentional action. But hey, who knows, who cares?
Hand Cannon: While the pistols of Halo are well known for being more effective than the Assault Rifles, the Reclaimer trilogy apparently now features the "M363 Remote Projectile Detonator", also known as the Sticky Detonator. This muzzle-loaded handgun fires a magnetic explosive charge that can be remotely detonated by the wielder.
Heroic Mime: Finally fully averted. John-117 speaks freely in and out of cutscene, though he does have a professional attitude about him.
- Dialog During Gameplay: Unlike any previous entry save Halo 3: ODST.
I Knew It!:
- Once Microsoft set Bungie free and created 343 Industries, fan theories focused around a Combat Evolved remake or this. Turns out we got both.
- Ever since the end of the Halo 3, fans assumed that the mystery planet would be related to Forerunners.
Mecha-Mooks: This is the first game to feature openly hostile non-Monitor Forerunner enemies, and they're still machines such as the Promethean Watchers, Promethean Knights, and Promethean Crawlers.
Nightmare Face: The true face of the Promethean-Knight. We are not responsible for any nightmares looking at it causes.
Won't Work On Me/So Last Season: The new Forerunner tech-based enemies called Watchers can throw grenades back at John if he doesn't shoot the grenades (or kill the Watcher holding it before it can throw the thing) to detonate them early.
Oh Crap: Remember that planet in the legendary ending of Halo 3? The one with all the Forerunner symbols that could be seen from orbit? Turns out it's still inhabited. And it's full of hostile Forerunner battle droids and Covenant Remnant forces.
- Everyone who studied Halo's expanded universe were probably less surprised about the planet.
- Meta-example: the game's creative director left the project about two months after it was announced. Fanboy cynicism has hit new highs.
OOC Is Serious Business: Cortana's This Is Sparta screaming. Not even in Halo: Combat Evolved when she angrily tells Master Chief, "Do you know what he almost made you do?" was she ever this out of control. It's probably a symptom of her oncoming rampancy.
The Remnant: Elites, Grunts, and Jackals are still around on Requiem from the Covenant Empire and still hostile to John-117, but the Covenant itself more or less dissolved four years ago.
Robot War: Gearing up to be one.
Scenery Porn: The Forerunner planet at the end of the trailer, continuing a proud tradition of the Halo games. Looks a lot like a fancy Unicron.
- If the E3 2012 gameplay reveal is any indication, this game will very likely surpass every previous Halo game in this aspect.
Sealed Badass in a Can: How the Master Chief starts the game.
Shout-Out: The Vision mode that Cortana activates toward the end of the gameplay trailer to see invisible Forerunner troopers is very similar to the multi-vision modes from Predator in look and activation.
Sinister Geometry: The Forerunners have a glowing Spheroid Dropship (implied to be a Cryptum).
Super Soldier: In addition to The Chief, Spartan IVs have been briefly alluded to being present in at least multiplayer, having first been mentioned at the conclusion of Halo: Glasslands.
- It seems that the Spartan IVs have arrived via crash landing on Requiem in the UNSC Infinity, so yes, they will also probably be appearing in single player.
Sprint Shoes: The "Sprint" armor ability can be used without taking up an armor ability slot now, unlike in Halo: Reach.
This Is Sparta:

Cortana: I will not! Allow you! To LEAVE THIS PLANET!

Trilogy Creep: Since Bungie never intended to go past a third game themselves. According to 343 Industries, this will be the start of a whole new trilogy, which means we can expect the series to go up to Halo 6, which means if there will be no other games there will be nine games total.
Took a Third Option: A good number of fans were disappointed when the DMR replaced the Battle Rifle in Reach, but it had its fans; on the other hand, the Battle Rifle has been praised as the "signature" weapon of Halo (really, they're almost identical; Rule of Cool is the only solid argument in the BR's favor). Instead of choosing one over the other, 343's solution was to add both in the next game.