These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Joseph Stalin is portrayed as every bit the ruthless, paranoid dictator that he was in real life, but excludes any redeeming qualities he had and makes him even nastier in some regards. He builds up the Soviet military machine and invades the rest of Europe to establish his totalitarian rule over the entire continent. He orders his security officers to test Sarin gas on a town of innocent civilians and the player to kill the survivors and raze the village. He also personally kills his lieutenants for any failure, orders purges of his entire military staff on a whim, and largely destroys the countries he invades as he did with Greece. When the tide of war turns against him, Stalin uses his troops as sacrificial lambs to delay the Allied advance long enough so he can destroy the major European cities with his newly-developed nuclear missiles and force a victory.
Crowning Music of Awesome: Is there anyone who, having played the original game, can read the page quote for Red Alert without "Hell March" beginning to play in their heads?
When playing as the Allies: Heavy Tank battalions. The basic Soviet tank already outclasses the Allied tanks, so you've got to rely on Light & Medium Tank swarms to take them down.
When playing as the Soviets: Apache helicopters. Because the Soviets dominate the air, the Allies are the ones who have good Anti-Air units in the form of Rocket Soldiers & Destroyers. The Soviets, however, only have one mobile AA unit: the Mammoth Tank, whose missiles are actually specialized to kill infantry, and thus aren't that effective against Apaches.
Good Bad Bugs: If you click at the right time you can get a grenadier to throw a grenade a ridiculously long way, especially in the MS-DOS version of the game.
The Tesla Coil seems to do more damage than the developers originally intended, with its lightning hitting multiple times per shot. This may have contributed to the weapon's popularity and later proliferation into other roles.
Moral Event Horizon: The Soviets. They cross the MEH roughly THREE SECONDS into the first cutscene of the first game. Or more accurately, even BEFORE the game begins which you learn of within the first three seconds of their first cutscene, where Stalin and his subordinates are discussing the effects of Sarin gas upon a few unfortunate civilian "test subjects." Right before ordering you to raze a Polish village to the ground and kill everyone that inhabits it. They get worse as the game goes on.
Older Than They Think: Red Alert 1's second expansion pack, The Aftermath, introduces many things that a lot of people think came in with Red Alert 2: Tesla Tanks, uncrushable Tesla Troopers (here called Shock Troopers), Demolition Trucks, chrono-capable vehicles (Chrono Tanks in this case) and more. And even Cyborg infantry, which many players think debuted in Command & Conquer: Tiberian Sun: the Soviet Super Soldier Volkov is a cyborg.
Paranoia Fuel: The Soviet campaign in the original is filled to brim with this. EVERY single Soviet character is looking for the chance for their own advancement, and mean Anyone Can Die at a moment's notice. And there's Stalin, who is the same paranoid lunatic he was in Real Life that we see does the same purges he was infamous for.
Zerg Rush: A popular tactic among Soviet players is to build nothing but a massive force of heavy tanks and overwhelm their opponent.