The Red Alert 1's portrayal of Soviets in general and Joseph Stalin in particular. The very first thing you see in the Soviet campaign is the aftermath of a Sarin gas test, with Stalin and his attaches going over the results. The first mission they give you involves burning a Polish village to the ground and killing everyone and everything inside. It only gets worse from there, as Stalin orders mass-production of the gas to exterminate entire villages and towns that resist the advancing Soviet army.
Another example of his unpredictable nature comes about during the mission he instructs you to capture the Chronosphere. When you do finally capture it, there is a cutscene showing it going unstable and then exploding. Cue Stalin angrily ordering that you be be executed, until the secretary informs him that one of the other officers gave you incomplete/faulty intel, whereupon he personally strangles the man.
In one cutscene, Stalin swings between drunken cheerfulness and deadly seriousness as he hands an officer a list of names to be purged while having some vodka.
During the Allied campaign, there is a tense series of missions whereupon you are tasked to rescue an officer who wished to defect from Stalin's regime, whereupon he confirms Stalin's plan to launch nukes at the Allies. It's the desperation in which he begs you to stop his former Premier that will unsettle you.
The worst part of the portrayals are when you realize that, unlike Red Alert 2 and 3, these were rather accurate and, more importantly, realistic. Stalin, in particular, proves to be a very accurate portrayal of one of the most frightening dictators in history. Also see Shown Their Work below.
The Chronosphere technology proposed by Einstein in this series has a horrifying side effect that is only seen in the first Red Alert: Every so often, the abuse of Chrono technology will cause a Chrono Vortex to form. An enigmatic swirling distortion in the fabric of reality itself, the Vortex will tear apart any troops, vehicles, and buildings that happen to be in its path as it meanders around the map. This unstable Chrono Technology also exhibits the side effect of killing all passengers inside any APC transports when you teleport them, in a parallel to the mysterious deaths attributed to the urban legends of the Philadelphia Experiment that were the inspiration for the Chronosphere.
Later "stable" versions of the Chronosphere seen in Red Alert 2 have an offensive bent that will terrify enemy commanders: Besides allowing a canny commander to teleport vehicles around, you can also use the Chronosphere to pick up enemy vehicles and send them wherever you please - it is entirely possible to drown tanks and shatter ships upon dry land with this technology wielded as a weapon. Furthermore, the effect of the 'stable' Chronosphere is deadly to infantry not in the safety of a vehicle.
Modified versions of Chrono technology as wielded by Chrono Legionnaires and the IFV with a Legionnaire passenger allow them to invoke the power of Retgone upon enemies, erasing them from time in the same fashion as how Einstein accidentally started the Red Alert timeline in his all-too-successful attempt to eliminate Hitler. The Paranoia Fuel invoked by a white-armored teleporting figure who erases things from existence could potentially cause some real freakouts.
One of the penultimate Soviet missions in the Counterstrike expansion, Paradox Equation, has you being assigned to capture a Chronosphere in a region badly warped by the effects of experimentation with it. How badly are we talking here? Try having every unit's weapons being altered into something completely different, like tanks with Tesla and Flame cannons, Artillery pieces firing oversized rounds, and V2 launchers suddenly finding their payloads boosted to near-nuclear levels. The mission briefing itself adds to the surreal horror:
TO: Field Commander S7 FROM: Soviet Command PRIORITY ONE We received this garbled transmission from a scout group sent into a suspected Allied test site: <TRANSMISSION BEGINS> All... te.t area di..overed! Chronos... test g... crazy! Weapons... effected by... air units inop... Area unst.able! Ch...osphere must be affect... <TRANSMISSION LOST> You are to investigate this. If the Chronosphere is indeed behind it, this is a perfect opportunity to capture it. See that it happens.
- Mission briefing
Both endings of the war have their own dark sides:
In the Allied victory, Stavros will encounter Stalin trapped under rubble, and proceeds to conceal him by gagging him and placing a rock to conceal his face, before lying to the soldiers on-site about there being no survivors; this was a pretty cold-blooded conclusion to the building grudge that he had been holding over the war crimes commited in Greece by the Soviet forces.
In the Soviet victory, Nadia's personality takes a terrifying flip as she suddenly breaks character once Stalin is rendered helpless by her poisoned tea, ranting loudly at him was she shoots his body repeatedly for the indignities she'd endured at his hands. Kane's sudden elimination of her is almost a relief after that.
Cut content from the first game's script involved a Last Stand of the Soviets as the Allies make a final gambit of teleporting their entire British-European army to Moscow, and their defeat as well as the capture of Chronosphere plans result in a terrifying retribution. Planned epilogue was the sudden teleportation of Soviet strategic bombers carrying nukes, made invincible by amplified Iron Curtain to obliterate multiple American cities destroying the United States once and for all, to the point that the last top brass attempts to kill Stalin in a horrified realization, only to be foiled by the player.
Red Alert 2
Yuri's Mind Control is rather frightening, considering the tactics of mind controlling enemies, civilians and what else to send them into a grinder or to increase power to your bio-reactors. Could cross into And I Must Scream when you think if they're completely aware of being mind controlled before being turned into a Living Battery or ground up for spare cash.
The intro of Red Alert 2, which is unskippable for the first-time run, has him brainwashing one of the American missile control staff, turning him into a blank stare while aiming a gun to his friend to threaten to self-destruct American's nuclear arsenal. The worst part is that you don't even need to be in his presence; a phone call is all he needs to mind control you.
A lot of Yuri's ideas for units are downright cruel and unusual along with exploding into a virus cloud, going berserk and killing your allies, being mind controlled, having your vehicle pulled to your imminent doom/mind enslavement, irreversible mutation into a muscular brute or just outright being enslaved to dig up ore and gems from the ground until hopefully some capitalist/communist comes along and destroys the miner you're enslaved to.
The beginning cutscene of Yuri's Revenge has him activating his network of Psychic Dominators across the world which permanently mind-controls pretty much the entire planet. Only a desperate last minute air strike on Alcatraz island (throughout a hail of Gatling Good fire) authorized by President Dugan manages to disable the Psychic Dominator located there, and that's only because a fatally-damaged Harrier crashed into the nuclear reactor and cut the power. The rest of the Harriers were all wiped-out to a man. Yuri came this close to completely winning and the only way to fix it is to travel back in time.
Yuri's ultimate fate in BOTH campaigns is unpleasant. If the Allied Forces win, the Americans imprison him inside a claustrophobic coffin-like psychic inhibitor to prevent him from mind-controlling any more people, his only concession being a clear window for him to look out from. If the Soviet Union wins, Yuri will steal the Time Machine and attempt to flee into the past, only for Zofia to overload it and send him so far back, he ends up trapped in the Cretaceous Period, and is last seen attacked by a Tyrannosaurus Rex.
Yuri in RA2. He's not as scary as Stalin, he's still a huge Knight of Cerebus amongst a bunch silly villains. He's extremely stoic, controls people's minds, and his voice alone just screams "this guy is evil, don't trust him you idiot." Of course, by the time you heard his voice, trusting and obeying him is no longer up to you... Probably the worst in the RA2 vanilla soviet ending is when we see him with his calm attitude when reduced to a Brain in a Jar. His faction has some of this with his Grinders, they break stuff down into material components...Including people.
One of his threats in the "Brain Wash" mission of Yuri's Revenge is particularly chilling. Knowing who Yuri is and what he can do, it's not an idle one.
General Vladimir, in the Allied mission "Last Chance", addresses the player with a chilling speech as he destroys Chicago.
"Hear me, you foul American phantom, wherever you are. You can work your armies like a puppeteer all you want, but this is my play! Here is the city that you have saved, without the Psychic Amplifier, which you so rashly destroyed, I no longer have much use for it. Behold. The power. OF MOTHER RUSSIA!!!"
The Virus's toxic sniper-round in Yuri's Revenge. It kills you and blows up your corpse into a cloud of poison gas, which can then infect other soldiers, who then blow and explode, releasing more poison gas...
Terror Drones are actually dismantling the vehicles, the crew just dies from the resulting explosion (that's why you have to repair them to get the drones off). However, note that the Drones were designed with Dismantling Vehicles in mind and was only suppose to do that. The butchering of infantry was when the Soviets realised the same tools used to cut through metal and sever cables can be used to do the same to human flesh and limb.
Yuri's Chaos Drones release poison gas that makes units go berserk and attack everything in sight.
Attack dogs and war bears. Imagine trying to fire your weapon like crazy at them before they lunge for your neck.
Soviet Desolators would be a horror to face in battle. No soldier is safe from the lethal radiation beam cannons they wield, and the Red Alert 2 incarnations of these deathbringers can slam their cannons into the ground and make a large patch of land so toxic infantry die rapidly. Their sadism and the sickly-green glow makes them seem even more inhuman.
The Soviets use Giant Squids as Attack Animals. They ensnare ships in their tentacles and rock it back and forth, ultimately sinking it unless it's rescued in time. The ship is utterly powerless in this state. Imagine being a sailor and this Sea Monster traps your ship and there's nothing you can do about it except wait for death or pray that you're rescued. And units who swim, like Tanya or Navy SEALs? Imagine you're swimming and a giant squid attacks you with the razor sharp suckers on its limbs and its sharp beak...
Yuriko Omega, she's a Person of Mass Destruction whose dialogue points to her not being completely mentally stable. It was recorded that amongst her personal kill-counts includes an entire Allied company including a mix of infantry, vehicles, attack helicopters, ships, and a school of Allied-trained recon dolphins.
Why do multiple Yurikos show up in the campaign? Because the Empire has been making clones of her. If you look closely at the Psionic Decimator, you can see that each pod contains a Yuriko clone, and the cloning facility is actually shown in Uprising.
After the main campaigns of the RA 3 story comes Yuriko's personal quest, Uprising. At the end of the main campaigns, the original Yuriko is taken prisoner by the Allied forces until she receives a telepathic message from her sister, who was also held in the Shiro facility, which engages in a variety of dehumanizing and brutal procedures to produce and train psychic commandos like Yuriko herself and her clones. She escapes from the Allies, and fights her way back through the facility, where she does succeed in freeing her sister. However, they have a falling-out, and Yuriko is forced to kill her sister in self-defense. About the only thing good that happens of this incident is that Yuriko destroys the facility that made her into a mentally-unstable psychic commando, preventing more clones of herself (and more psychic commandos) from being produced.
The effects of the freeze beam and shrink beam. Imagine getting frozen alive, and can only watch in horror as a man with a shotgun comes up to finish you off. Or imagine you're in an apocalypse tank, crushing Capitalist pig-dogs, when all of a sudden you're shrunk to the size of a kitten, and see guardian tanks coming up relentlessly as your shells ping off their armor harmlessly.