Take Earth from the Command & ConquerTiberium setting, as of the end of Command and Conquer 3: Tiberium Wars, and put it in the Mass Effect setting, following the same timeline. The result? Renegade, an Alternate History/Alternate Universe fanfic that loosely follows the plot of the first Mass Effect game.The year is 2183. The Global Defense Initiative, having formed a unified global hegemony on Earth, discovers Prothean ruins on Mars, which jumpstarts their already-advanced technology and allows them to escape the ecological hellhole that Earth has become thanks to Tiberium. Making their way into the stars, they run afoul of the Turian Hierarchy and the rest of the Citadel species. With their advanced technology and the economic power of Tiberium, GDI becomes a major independent player in galactic politics, presenting an ally for disaffected species like the krogan and Quarian Migrant Fleet. However, things aren't all rosy, as GDI finds itself locked in a drawn-out war with the Batarian Hegemony, and in the shadows, the Brotherhood of Nod is emerging, manipulating events from behind the scenes....The story opens with then-Lieutenant Shepard, a biotic GDI Commando who finds herself forced to accept the assistance of the Brotherhood of Nod when slavers attack Elysium, and as a result is catapulted into heroism and fame. Seven years later, on the way to the GDI colony world of Eden Prime alongside a Council Spectre, she discovers an old enemy has emerged and attacked the human colony: the alien Scrin, working alongside the synthetic geth and a mysterious alien dreadnought.Written by the same author behind Tiberium Wars and Forward. Notable for the level of depth involved in depicting the effect that a GDI-led humanity would have on the galaxy. It is indicated that this universe's Earth is set after the "good" ending to Tiberium Wars where the Liquid Tiberium Bomb was not used. The story also draws a great deal of inspiration from the canceled Tiberium game, using various designs, weapons, and uniforms from the game, such as the Integrated Combat Suit and a variant of the GD-10 weapon.Archived story thread on Spacebattles can be found here, and Fanfiction.net version available here.Has two official Broad Strokes prequels written by Charnobyl: Eagles Fall, which covers the Shanxi War between GDI and the Turian Hierarchy, and The Verge War, covering the war between GDI and the Batarian Hegemony.Not to be confused for the television series.
Examples of tropes in this fanfic:
Adaptational Badass: Though she was pretty badass in canon, Liara's tough enough in this story that she's able to stare down Urdnot Wrex and convince him to stay and fight to defend her science team just by having that much steel in her spine. And this is before she's ever met Shepard.
All There in the Manual: Each chapter has a Codex entry at the end, similar to Mass Effect's, which details information that wouldn't be readily clear in the fanfic's narrative. The Spacebattles discussion thread also has some additional background information scattered throughout it.
And by "similar to", we mean "many of them are actual Mass Effect codex entries, re-written with GDI's impact".
Alternate Universe: Fairly obviously. Among the other things, GDI is friendly with both the quarians and the krogan, Shanxi was a bloody ground war due to GDI's heavy armor and orbital ion cannons, the Batarian Hegemony is at war with GDI, Miranda works for the Brotherhood of Nod, Kaidan is a Tiberium mutant, Akuze was a Scrin attack, Wrex and Jacob are on Eden Prime during the geth attack, Nihlus survives, Jacob takes Ashley's place on the Normandy, Charles Saracino is on the GDI Director's Board, and Garrus is a Spectre. Note also that this story ignores the events of Tiberian Twilight.
There are a number of smaller, aesthetic differences too, i.e. the Normandy's interior lighting is cold blue-gray and their haptic interfaces are blue instead of orange.
Amusing Injuries: As with Tiberium Wars, the dim lighting and constant floor-level mist exist solely because Kane finds it hilarious that people keep bumping into stuff. It turns out that both Kane and Miranda have omnitool modifications that let them spot things hidden in the mists so they don't stumble.
Apocalyptic Log: A Nod Marked of Kane cyborg leaves one on the colony of Eskirk while dying, detailing the Collectors' arrival.
The Batarian Hegemony did this when they kept supporting raids on human space. And it turns out that the batarians were only fighting two of GDI's eight standing fleets. And this is before GDI starts mobilizing for full-scale war due to the geth attacks and Kane bringing out Temple Prime. When the latter two events happen, GDI rolls out the Ninth Fleet and begins building and training the Tenth and Eleventh battle fleets within a three month period to finish the batarians off.
Speculation (partially supported by Word of God) is that the Scrin are hiding specifically to avoid doing this to the Reapers. And unfortunately, they seeded the wrong world with tiberium....
A more villainous example is the Collectors starting the harvest a few years earlier than expected. And Kane suspects that he actually caused them to attack by revealing Temple Prime.
Awesome, but Impractical: Firestorm barriers, per Word of God. Their power draw is enormous and they only go in one direction, and the projectors are still vulnerable to enemy fire, making them only really useful as a surface defense system with the projectors armored and buried underground. The Firestorm can be angled to create a pyramid-shaped defensive dome, but this won't work on spacecraft because they can be attacked from any angle, and the shield would draw about three times as much power as the rest of the ship's systems put together.
Badass Army: GDI and Nod. The former fought the Turian Hierarchy almost to a standstill on Shanxi, without much understanding of mass effect technology. The latter is implied to have some incredibly badass troops (if lacking in the raw numbers and sheer firepower of GDI). When asked what Nod's troops were like, Peptuck's response was to put up pictures of Adam Jensen, the Point Man, and a Spartan.
Badass Bystander: Two C-Sec officers in a lightly-armed emergency-response aircraft, who take one look at the Scrin's anti-air capability and then attack.
Badass Longcoat: The Nod commandos under Miranda's command have armored longcoats over regular combat armor and ballistic fabric.
A whole slew in Chapter 12, with Marked of Kane rescuing Miranda from Intruders and Garrus and Kal'Reegar saving Shepard, Tali, and Michel from a Corrupter. Also subverted when Galorus and Valerian are immbolized by a gun walker. The GDI Orcas arrive a split-second too late to save them.
Both Sides Have a Point: The author's view on GDI and Nod (as well as the conflict between humanity as a whole and the Citadel). The author has actually stated a variation on this, which is that neither side is right, but both are wrong on certain points.
Broad Strokes: Word of God is that canon has been "massaged" to allow for a better story, with things like precise numbers and weapons yields being glossed over to create a stronger and more realistic drama. For example, when one reader complained that the salarian STG were so easily defeating GDI information security, the author replied that the STG had been infiltrating other species' security networks for a thousand years and were using advanced computers when humanity was still using the abacus. They should be running rings around GDI in the intelligence arena. In addition, Red Alert events have been oh-so-briefly mentioned in passing, with deliberate mention that the events of Red Alert broadly apply to the setting.
Chandler's Law: The assassins/kidnappers who hijack Shepard and Anderson's aircar appear to be following this.
Continuity Drift: The original version of the story specifies that the turian Councilor's name is Velarn, but it wasn't until Mass Effect 3 came out that we learned that Velarn is the salarian Councilor's name.
Continuity Nod: There are a number of references to Eagles Fall, such as a turian naval officer who was the son of the turian admiral in charge of the battle at Shanxi, as well as Locke, alive and well and apparently working for Phoenix. Also, Word of God confirms that Anastacia Telfair is the descendant of Sandra Telfair from Tiberium Wars. Later on, there is also Captain Aldis Rawne, a descendant of Commander Rawne from the same story, as well as several references to the omnipresent mist and dim lighting in Nod facilities (itself a Running Gag).
Continuity Snarl: That being said, there's some divergence between the two fics when it comes to the minor details, particularly the timeline in Eagles' Fall, which does not mesh precisely with the timeline in Renegade. Somewhat assuaged because the timeline appears to be a GDI public-access historical record.
Cowboy Cop: Garrus, which is lampshaded, as the chapter in which he first showcases his... "enthusiasm" is titled "Cowboys."
Death World: The general perception of Earth is that it's an even deadlier world then Tuchancka with one of the key differences being that when presented with the possibility of getting off the planet like the krogan a large portion of the human population chose to stay put. Which of course lends itself to the perception of humanity as a species of crazy BAMFs by the rest of the galaxy.
Disproportionate Retribution: Standing GDI military doctrine calls for overwhelming force in response to any attack, up to and including launching a full-scale war on one of the major galactic powers like the Batarian Hegemony.
Zig-zagged when it comes to Corporal Jenkins. See below.
Dying Moment of Awesome: Corporal Jenkins gets one when he gets hit by an EMP blast, then slaughters seven Geth, including one destroyer, before Saren's buzzers kill him.
Dynamic Entry: Garrus and Zaeed are both fans of this kind of entry. Locke's Phoenix team uses this as well when they ambush Miranda's squad. Pops up so often in Chapter 12 that the chapter is even titled "Dynamic Entry." The Scrin Battlemind also favors this method of entering the battlefield.
Shepard working with Nod in the prologue to rescue the captives from Elysium. Of note is that Shepard is pretty much forced to do this; she's been stripped of her weapons and gear and is on a Nod ship, and they make it clear that she can either go along with them or bad things will happen.
Zaeed pulls this with Jacob and the GDI Marines in Chapter 9, while storming the warehouse. Both Shepherd and Jacob are alert for him to doublecross them. He does, but is foiled by Alenko.
Garrus' shift from a somewhat impetuous Cowboy Cop to "Jack Bauer meets the Kool-Aid Man" appears to be a direct result of GDI's presence in the timeline. Thanks to GDI aggressiveness, the Council expanded the number of Spectres, and he was given an opportunity to join. He made the choice to become a Spectre, and as a result never got the instilled restraint he would have otherwise received as a police officer. The result is a Spectre who, despite retaining his canonical friendliness, is about as subtle as a brick through a stained glass window.
To a much lesser degree, there's Jacob Taylor. In the traditional ME timeline, he joined the Corsairs because he thought it would cut down on the red tape that the SA puts on its military, and left to join Cerberus when even Corsairs proved little better than the Marines. In the Renegade timeline, the GDI's time honored tradition of "Step 1: identify problem. Step 2: apply military force. Step 3: repeat Step 2 until problem ceases to be problematic," seems to have prevented Jacob from ever wanting to leave the standard military.
Zaeed's presence on the Citadel is apparently as a result of this. Due to GDI's friendliness with the krogan, Wrex got a job on Eden Prime as a bodyguard. As a result, Zaeed was the one hired by the Shadow Broker to deal with Fist.
Tali has already completed her pilgrimage when the story starts, which means rather than a sole Quarian on the run from Saren, she had a team of Migrant Fleet Marines with her, of which Kal'Reegar is the only survivor. This also explains the larger merc presence.
Also the plans for the invasion of Rannoch are happening much earlier thanks to GDI support
Thane is a Citadel Spectre in this timeline.
Frickin' Laser Beams: Nod laser weapons are particularly devastating as everyone uses kinetic barriers, which don't block them. Also, Tali packs a Nod laser weapon.
From Bad to Worse: The story starts out with things bad, with the Scrin backing up the geth and Sovereign on Eden Prime. Then the Scrin attack the Citadel itself. Then the Collectors start showing up a whole lot earlier....
Gambit Pileup: The Reapers are plotting something. Kane is also plotting something. The Shadow Broker got involved when sending Zaeed after the mercenaries, and there's also Phoenix, the Renegade-incarnation of Cerberus. The quarian Migrant Fleet is hiding something. At the moment, GDI is just scrambling to keep up. And now the Collectors have joined in....
Gatling Good: The MAWS (Multibarreled Antiarmor Weapons System) which is a four-barreled railgun that has the added option to let all four barrels be fire at once. It is massive, requiring a regular human or humanoid without powered armor to wear special strength-assist attachments on their armor to handle it.
Both Shepard and Jacob cooperate with Zaeed's rampage - or at least stay out of his way - but anticipate he'll turn on him when the Enemy Mine is over. He does, and is also Genre Savvy enough to backstab Shepherd when Jacob's Marine platoon is too far away to intercede. Until Alenko showed up...
When Shepard fends off a force of Scrin, she keeps her weapon trained on the hole they came through, fully expecting more to arrive when they turn their back. They do.
Gilligan Cut: In Chapter 15, when Shepard finishes listening to the distress call from Liara's expedition, she wonders if anyone is still alive because the distress message was sent an hour ago. Cut to Wrex beating the shit out of a Scrin Intruder with a big grin on his face.
Grey and Gray Morality: The author has made it quite clear that neither GDI nor Nod are complete good guys or villains. In fact, Nod seems to get more positive points than negative ones in this timeline, though in his commentary the author notes that both the Brotherhood and GDI are different entities than they were in the Command & Conquer games, being separated by more than a hundred years.
In one of the author's own comments, he said that (paraphrased) "Neither side is right. However, both sides are wrong on certain points."
Sparatus: No Citadel species has been so incompetently self-destructive as to let its homeworld be consumed by a mindless crystal.
Not a huge surprise: Sparatus is, in canon, most known for being Air-Quote Turian.
Had To Be Sharp: Part of what makes humanity so tough is that they survived on the only planet in the galaxy more lethal to organic life than Tuchunka.
Hauled Before A Director's Board Committee Shepard is brought before a Director's Board committee to testify regarding her encounter with Kane. There's a not-so-subtle attempt by the more paranoid Board members to accuse her of being a Nod sympathizer.
Hilarity Ensues: Word for word, when Garrus goes into Chora's Den after Fist.
Identical Grandson: Lieutenant Anastasia Telfair's description almost exactly matches that of Lieutenant Sandra Telfair, her ancestor from the Tiberium games, save for having some blonde streaks in her hair and blue eyes. Captain Aldis Rawne, a Nod ship captain, also closely resembles Commander Rawne from Tiberium Wars.
Immune to Bullets: The Scrin Corruptor can repair itself extremely fast. It takes heavy explosive ordnance from multiple sources to finally put it down.
Incoming Ham: Kane announcing to the whole galaxy that he's still alive by hacking into the holoprojectors in the Council Chamber.
I Shall Taunt You: According to Word of God, Councilor Sparatus' Jerkass tendencies are actually deliberate efforts to piss off humans so they don't think clearly. It works on Udina, that's for certain.
In Spite of a Nail: For all the differences noted under For Want of a Nail, the story does still stick to the same canon events that kicked off the first Mass Effect game, with Sovereign and Saren attacking Eden Prime. Afterwards, though....
Insult Backfire: A political variation; the Council snubbed GDI, restricting their attempts to get an Embassy on the Presidium by refusing to allow armed GDI guards. GDI instead took out a much larger, roomier, and nicer Embassy on the Wards in a private building that let them maintain a few hundred armed guards instead.
All of the Scrin sect known as Reaper-18 exhibit these traits, with warrior forms that can wade through small arms fire without slowing (Intruders) take dozens of grenades without stopping (the Ravagers), can actively regenerate from any injuries and require antitank weapons to put down (Corrupters) or simply tanking fire from entire GDI platoons, complete with biotics, and not even giving a damn (the Battleminds).
When Sovereign attacks Eden Prime, it takes a direct broadside from a GDI orbital defense platform, which has six dreadnought-grade ion cannons on it, without blinking.
Invisibility Cloak: Both Nod and GDI appear to have these (with GDI's apparently restricted to ship-based operations) Also, Tali has one.
Garrus: "Fist, we're all adults here. Let's not lie to each other. It'll just lead to tragedy for your limbs. I know you're working for Saren. Now tell me why."
Subverted with Zaeed. When he questions Fist, he tells him that Fist is a dead man already. Then he takes out a knife and sets it down next to a pillow, then tells Fist that if he talks, he'll get the pillow, and if he refuses, he'll get the knife.
Jetpack: GDI makes near-ubiquitous use of these in all their armor, with the rest of the Citadel species moving to adopt them in special operations units once GDI proved their effectiveness in the First Contact War.
Kill Him Already: Both Jenkins and Shepard make this mistake when confronting Saren by covering him with their railguns and demanding he surrender instead of outright shooting him. In the former's case, it gives Saren time to use an ECM pulse to make his weapon think it is overheating, while in the latter, it gives Saren time for a Scrin Mastermind to arrive and teleport him away. Shepard berates herself for this mistake immediately afterward, saying she should have shot Saren right away, and Nihlus responds by saying that yes, she should.
Knee-capping: This is Garrus' approach to most situations where someone needs to be kept alive.
Loophole Abuse: Temple Prime doesn't technically violate the UHAT treaty, because it isn't a warship.
MacGuffin: The Tacitus buried on Eden Prime. Lampshaded in the author's Spacebattles chapter guide.
Made of Iron: Scrin Intruders and Ravagers. One of the former takes multiple pistol rounds, several shotgun blasts to the head, and two frag grenades to kill. The latter can take all of the above and keep on coming.
Kane. When you're the head of an infamous terrorist/criminal/fanatical religious organization who manages to steal the Tacitus, one of the most valuable artifacts to both the Citadel and GDI, then turn around and negotiate a compromise between the two to make yourself look like the reasonable and level-headed one, you're a definite case of this. In fact, this is pretty much Kane's entire methodology, as he doesn't have the massive base of support he had on Earth, and is forced to play the role of secretive manipulator using his minimal resources to make himself look bigger than he really is.
Shepard is implied to be one of these. She is very good at manipulating others and knowing how to keep negative personality traits (such as Garrus' and Admiral Parker's tendency for overkill) under control.
Mind Hive: The Illusive Man/Jack Harper, who apparently found "something else" when he attempted to access the Scrin's communications network.
Mighty Glacier: The appropriately named Glacier-class dreadnoughts fielded by GDI, which are described as having an almost impractical amount of firepower.
Mini-Mecha: The REV12 Wolverine and the Turian Hierarchy's Steelclaw knockoff.
More Dakka: The GDI looked at the other races, and saw how (as in canon), it was possible to make weapons shrink to take up less space. For example, a pistol could shrink to the size of a deck of cards, or an assault rifle could shrink to the size of a shoebox. They looked at this miniaturization technology, and decided that instead of taking a weapon and making it smaller, they would keep the weapon the same size and add more gun.
A lot of material is based on content from the canceled Tiberium game: The Werewolf weapons are based on the Swiss-Army Weapon the protagonist used, Nod armor and uniforms are based on their designs in the game, and the Scrin's Intruders are modified versions of the humanoid enemies with the same name in that game.
On a more serious note, whatever happened on Akuze. All that we know so far is that it involved Tiberium, the Scrin, and Shepard's face getting horribly scarred by Buzzers.
Not My Driver: This happens while Shepard and Anderson are leaving the Citadel Tower, where the two GDI soldiers driving their aircar are actually badguys who ambushed the actual aircar driver/escort and took their armor.
Not So Different: Saren says this to Nihlus during their second confrontation. Interestingly enough, Nihlus seems to agree.
Obstructive Bureaucrat: Both the Council and the GDI Director's Board, particularly when they find out about the Tacitus.
The Citadel Control officer refusing to allow the Kursk's Orca compliment to assist in the Embassy battle because they don't have clearance - up until Nihlus comes in and grants authorization, at which point the bureaucrat is happy to let them launch.
Oh, Crap: the general reaction among GDI and the more informed aliens when Kane reveals himself.
Also the reaction of many of the readers when they realized that the Scrin and the Geth are working together and augmenting each other's tech.
Shepard has this reaction at the thought of Garrus and Havoc (the fifth) being in the same room. Two Crazy Awesome character working together nearly causes her to hyperventilate.
The Omniscient Council of Vagueness: Phoenix, which may or may not be this setting's analogue to Cerberus. Their intentions and motivations are stereotypically mysterious, but they appear to be hostile to Nod, or at least Kane's followers. And as with Cerberus, they are lead by Jack Harper, who is... different.
One-Man Army: The first chapter has Shepard holding off five hundred Batarian slavers with "her rifle and shouted profanity", and it just gets better from there.
Off the Rails: The story follows the original Mass Effect plotline fairly closely, right up until chapter 6, when Kane shows up. Shortly afterward, we have an insane wall-smashing Garrus helping Shepard track down Tali and Kal'reegar, and attack on the GDI Embassy by the Scrin in which Shepard is (briefly) killed, and GDI and the Quarian Migrant Fleet teaming up to go after the geth while Shepard chases down Saren.
Poor Communication Kills: Literally. Nod and Phoenix are violently hostile to one another, but in Chapter 12, both Miranda and Locke are trying to assist the GDI Embassy against the Scrin. Miranda is killing Masterminds to keep them from teleporting in reinforcements, while Locke is trying to analyze the Masterminds so that the Illusive Man can hack them and do the Scrin equivalent of a [DDoS] attack. Then again, from Miranda's reaction to Locke's arrival, neither Phoenix or Nod are exactly on speaking terms.
Ramming Always Works: Udina, surprisingly. He manages to take out the Battlemind by ramming an aircar into it, sending both twenty feet until they hit a wall and causes the Battlemind to stain everything in a twenty-foot radius with silvery gore.
Running Gag: Garrus raids a series of warehouses by crashing through the wall of each one in a "borrowed" car. The flashback to each is recounted identically, until Shepard catches on and tells him to just skip the rest.
Whenever a character thinks about Admiral Parker, the words "strategic" and "collateral" tend to appear in the narration.
Scars Are Forever: Shepard's face is severely scarred as a result of her experiences on Akuze apparently due to a close encounter with Scrin buzzers. Shepard was offered the chance to have her scars removed, but chose to keep them as a reminder.
Schedule Slip: The story suffers from this, with a lengthy wait between some chapters, and at one point the author's computer crashed and he lost an entire chapter. He poked fun at this in the next update.
To quote Shepard: "Most little girls had dolls. I had a datapad with The Prince."
Kane references Star Wars while talking to Saracino, saying that "Director, I find your lack of faith disturbing." He's grinning the whole time, so it's quite clear he knows what he's referencing. Jacob even lampshades it.
When Locke's team drops in during Chapter 11, they use something suspiciously similar to the Icarus Landing System. Miranda's augmentations bear more than a passing resemblance to JC Denton's nanotech augments.
Space Cold War: Between GDI and the Citadel. There was a cold war between GDI and the Batarian Hegemony, but GDI didn't take those slaver raids very well....
Standard Sci-Fi Fleet: Word of God has laid out that the different navies of both GDI and Nod have distinct compositions and doctrines. GDI's fleet primarily consists of carriers and lighter ships, with an emphasis on base-hopping and resource and convoy interdiction, with enormous, heavily-armed fleets for destroying hardened targets and "super-heavy carriers" based on MCV technology that are designed to supply cluster-wide operations. Nod, on the other hand, uses larger numbers of lighter cruisers, complete with long-range fighters and light carriers, with an emphasis on destroying enemy supplies and support and avoiding a decisive engagement, causing the enemy to waste resources and spread himself thin defending against constant attacks. Both navies make use of MCV/Crawler technology to let them operate deep in enemy territory.
The Stations of the Canon: One issue witht he story is that it cleaves very closely to the original Mass Effect timeline despite the butterfly effect of GDI and Nod's presence in the setting, with the attack on Eden Prime happening at the same time as it did in canon and only marginally deviating from that at first. However, by the sixth chapter, the story starts rolling off the rails with things like the introduction of Kane, Spectre Garrus Vakarian, Kal'Reegar and a large group of quarian marines escorting Tali, Zaeed, Locke and the Phoenix organization, and a Scrin attack on the Citadel.
By the "Ghosts" interlude, things have leapt completely off the rails, with the Collectors starting their attacks a couple of years early.
Stealth in Space: Both Nod and GDI appear to have one-upped the original timeline's stealth systems; GDI has finally cracked Nod's stealth tech to develop a working optical cloak, used in conjunction with the thermal cloaking the original Normandy had. Complete with an early throwaway line about SIS being "impossible".
Story Breaker Power: Both GDI and Nod's sheer industrial capacity and raw firepower is downplayed. In canon, even outside of Gameplay and Story Segregation, it takes all of 3 minutes to make a Mammoth tank. Peptuck made it clear that he deliberately nerfed them for story purposes, because canon C&C manufacturing speed and firepower would break the story. He summed it up with the simple phrase "story > biggatons."
Sufficiently Advanced Alien: The Scrin in general. Most of their technology is a completely out-of-context problem for the Citadel and even GDI. No one really has any idea how to counter something that can casually teleport past your defenses and mind-control entire groups of people instantly. Plus, they have some kind of Mastermind variant that can hurl launch things in the air with blasts of raw kinetic force, which apparently doesn't involve biotics or mass effect technology.
In the background, the turians were caught a bit off-guard when they tried to assault Shanxi and ran headlong into orbital ion cannons for the first time. Unfortunately for GDI, the turians adapted pretty quickly, and Sovereign is easily able to bypass the GDI defenses by taking advantage of the ion beams moving at c to stay several light seconds out of range, taking out the ion arrays with kinetic rounds, then moving as the GDI guns spot them and return fire.
Word of God regarding the Scrin is that the forces seen in-game in Tiberium Wars are the equivalent of a few hundred mercenaries with armored cars and assault rifles, and the true Scrin armies and navy are "an entirely different beast." Among their assets are phasing tiberium kinetic impactors with liquid-tiberium cores, short-range teleporters, phasing technology, rift missiles, and some of them use large-scale versions of the Masterminds' mind-control rigs. The implication is that the Scrin are preparing for war with the Reapers.
Kane revealing Temple Prime, a two-kilometer long space station which comes out of nowhere and pretty much sends everyone scrambling to respond and figure out how the hell he managed to build it.
Swiss-Army Weapon: The Werewolf rifle used by GDI troops is essentially a fusion of the ZF-1 and the GD-10 from the canceled Tiberium game.
Take That: Chapter Three's Codex entry has a jab at the canceled Tiberium game when referencing the GD-10, saying the original product was canceled for "failing to meet quality standards."
There's also the obligatory shot at Mass Effect 1's elevators, including a reference to the Elcor Hamlet ad.
GDI is still driving around "house sized masses of fuck you." (While they have not yet been described with the full phrase, the standard description is still "house-sized". Make of this what you will.)
Theme Naming: GDI's naming scheme for their big ships. Supercarriers' classes are named after planets, while the ships themselves are named after mythological figures, i.e. the Mars-class supercarrier GDC Krishna. Dreadnought classes are named after terrestrial bodies, with the smaller dreadnoughts being named after cataclysmic events and the bigger ones being named after apocalyptic ones. So you get Mountain-class dreadnoughts named GDD Tunguska or GDD Sarajevonote Apparently named after the liquid tiberium detonation in Tiberium Wars, and Glacier-class dreadnoughts GDD Ragnarok and GDD Tiber Rivernote after the site where tiberium hit Earth.
There Is No Kill Like Overkill: GDI's approach to warfare is pure, unrelenting firepower coupled with Disproportionate Retribution. For comparison to the original timeline, the assault on Torfan was a costly ground attack through the pirates' tunnels. In this timeline, Torfan's base was orbitally obliterated by an ion cannon barrage that destroyed the complex and everything within fifty kilometers of the base. GDI, furthermore, has twenty defense platforms surrounding the Charon relay, each with six dreadnought-grade ion cannons on it. They're very serious about possible invasion.
Interestingly, this is pretty much the opposite of the Systems Alliance's doctrine, which emphasized flexibility and mobility.
Garrus has... markedly less restraint than in canon.
This is Admiral Havoc V's general approach to most situations. Worryingly, he assumes everyone follows the same mindset. Unsurprisingly, he and Garrus become instant friends.
The Protheans apparently used ion cannons as point defense guns.
There Was a Door: Silly mercenaries. Garrus has no use for your doors when he has a cargo hauler.
The Scrin Battlemind uses this as its primary means of getting around. Garrus eventually gets annoyed that it's stealing his schtick.
Took a Level in Badass: Well...everyone. But especially Garrus, humanity, and Kaidan. Goodness, Kaidan. Once a soft-spoken biotic Marine, now a soft-spoken GDI biotic Marine who happens to be a Tiberium mutant and can toss around Wolverine walkers like they're made of Styrofoam.
Touched by Vorlons: The Tacitus results in this, as it physically alters Shepard so that she adapts to her augments faster, as well as lets her activate and control Prothean technology. It even goes so far as to give Shepard ghost-memories and impart emotional reactions like antipathy toward an augmentation lab on a Prothean ship.
Trojan Horse: The Scrin use the turian cruiser Valedictum as one, assaulting it and taking it mostly intact and mind-controlling the crew to let them get close enough to the Citadel to start teleporting troops into the GDI embassy, apparently to kill Tali.
Tron Lines: Kane insisted on having the Marked of Kane have these.
Garrus would like to do one of these, but he thinks it's unprofessional, so he abstains.
Later, he does an inversion, as he walks towards a Scrin Battlemind, deftly sidestepping and ignoring the aircars being thrown at him.
We Are Everywhere: Nod. They can apparently alter communications from the Citadel at will to obfuscate what happened at Eden Prime, and later manage to get a building-sized hologram of Kane to appear in the Council Chambers. Ultimately, subverted. Kane's resources are not as extensive as they look, and he uses spectacular displays and his reputation to disguise his limited true capabilities.
What the Hell, Hero?: Shepard gives a minor one to Garrus when he blows out the electronics of the car that the kidnappers are driving.
Word of God: Lots of hints are dropped by the author in the Spacebattles discussion thread. On the other hand, the author is also extremely evasive on some questions, at some points outright saying "I dunno."
Word of God is actually Shrug of God when it comes to Shepard's appearance; with the exception of being female, severely scarred, and a biotic, all other details are left ambiguous so the reader can insert whatever appearance they think is appropriate.
When asked about how fast GDI's build times were, Peptuck's response was "Fast but not too fast. And no, I'm not going to be any more specific than that."
Peptuck has confirmed that Kal'Reegar will join Shepherd's crew alongside Tali.
Xanatos Gambit: Nod taking the Tacitus from Eden Prime, causing conflict between GDI and the Citadel that allows Kane to walk in and negotiate a compromise, thereby coming off as the reasonable and diplomatic one to interstellar politics. Kane even outright admits this to Shepard, who is forced to acknowledge that she can't act on the information because it make her look bad or ruin the compromise and only serve to make Kane look better.