I often thought about why do Americans love horror movies, especially those about zombie apocalypse.

I often thought about why do Americans love horror, especially zombie apocalypsetic type horror.

I foind it funny that there’s such a movie award aslike Saturn that aggregates such genres as horror, science fiction and fantasy – Harry Potter vs Saw (in hell I’ll be in a good company).

I’ve read a theory that this (cruelty and filth in media) is a way to control people.

"This" is used to refer to something that was mentioned before. You didn't really mention cruelty and filth before.

They (cruelty and filth in media) paralyze people’s will to resist.

Not wrong, but redundant since you already said it in the previous sentence

I also watched a documentary a long time ago.

The author (American) researched the problem of shootings in public schools and coame to athe conclusion that Americans is a nation of fear. / The author, who is American...

Better to use commas here since I think parentheses are better used to provide details that aren't directly related to the sentence and aren't that important to its meaning.

"The" since you're referring to a specific conclusion, instead of just a general conclusion

I also had my own theory – that this is a way to keep the nation in a shape – if It needsnecessary, zombies will give way to the Russians or the Chinese or somebody else.

But I really think that the problems of the world isare largely due to problems USA in itin USA's satellites.

I suppose on your side (of the Moon) many peoplmany people on your side think it's due to / because of Russia, isn’t iright?

"Isn't it" and "right" are similar in that they're both asking the listener for agreement, but generally "isn't it" is used when you're referring to something more specific.
Ex: This is your ball, isn't it?

The USSR had on its side states of Warsaw Pact and a few states ofin Africa, Asia and South America. / States in the Warsaw Pact and a few states in Afrikca, Asia, and South America. were on the side of the USSR

Today, the former states of WP and USSR are (now) members of NATO.

The whole world is against Russia!

Eggs increased in prizce dramatically!

The men without weapons: We’re Americans.

The men with weapons: Well, what kind of Americans?

I often thoughtwondered why do Americans love horror films, especially ones concerning zombie apocalypses.

or if you want to go even more literary: pondered

I found funny that there’s such a movie award as called "Saturn" that aggregates such genres such as horror, science fiction and fantasy – Harry Potter vs Saw (in hell I’ll be in a good company).

(in hell I’ll be in a good company)
what do you mean by this?

I’ve read a theory that this: (cruelty and filth in media) is could be a way to control people.

They (cruelty and filth in media) paralyze people’s will to resist.

I also watched a documentary a long time ago.

The author, who was (American), researched the problem of shootings in public schools and coame to athe conclusion that Americans is a nation of fear.

more than one: shootings

I also hacreated my own theory – this is a way to keep the nation in a shape – if It needs,be it, the zombies will give way to the Russians or, the Chinese or somebody else.

Don’t take it to heart,; I’m not entirely serious.

But I really think that the problems of the world isare largely due problemsto the USA inand its satellites.

problems (plural)

I suppose on your side (of the Moon)world), many people think it's due to Russia, isn’t it true?

due to

The USSR had on its side states of the Warsaw Pact and a few statcountries ofin Afrikca, Asia, and South America.

Today, former states of the WP and the USSR are members of the NATO.

Russia is wrapped up in sanctions, the mosthas countless sanctions imposed against it, the majority of its great territory is as suitable for human life less thanas Alaska or Greenland, but at the same time, it has more population and how large of a share of the world GDP does it hasve?!

EPrice of eggs increase in prizes dramatically!

I beg you! ) ¶
They said that America is being waited a “civil war” or reassembly.wasting away by being in a “civil war”.

They said it wouldn’t be a war-war like in… some other places of the world.

some is always plural

Just a part of elite (members of ruling class as called them a friend of mine called them) lost their power and sources of income .¶
I saw a movie trailer yesterday.

The movie (was) called Civil War.

This is not a complete sentence but I count is as correct because this is the style of the piece