Children nowadaysNowadays, children spend a lot of time withplaying video games.

The placement of “nowadays” is just a minor correction, don’t worry about it too much. It just makes the sentence sound a little more natural.
As an alternative to “playing video games” you could say “on video games”. “With video games” isn’t quite right...

They felt many emotions such asel things like excitement, happiness and fear when they played video games.

Use the present tense, since this is a general statement. It doesn’t only apply to children in the past, but children today, and in the immediate future too.

But İt'sit means that they can become addicted withover time.

“it’s” means “it is”. “Its” means “belonging to it”. In this case, you mean neither of these, so you don’t need an “s” on the end of “it”. Put an “s” on the end of the VERB when talking about the action of a 3rd person singular object (for example “it”).

This situation is very dangereous.

You don’t really need to specify “situation” here. It’s implied.
Mind the spelling of “dangerous”. You have an extra “e” here. =)

BThis is because they don't want to do their dutyimportant things such as do homework, going to school, help youand helping their parents.

Try not to start a sentence with “because”. Instead, say “this is because”. Alternatively, you can put a comma at the end of your previous sentence like this:
“This is very dangerous, because they don’t want to ...”

Additionally they don't want to play real games with friends.

That's sois means that children's social communication skills may weaken.

Use “that’s so” when you’re giving a reason for doing something. In this case, you’re trying to give an explanation, so say “this means that”.

They feelt many emotions such as excitement, happiness and fear when they played video games.,

The rest is written is present tense, so this likely should be too :). Alternatively, to highlight that playing in the past leads to them playing in the future, you could write:
"They have felt many emotions such as excitement, happiness and fear when they have played video games,"
This isn't how this would usually be written though.

Sso they want to play video gamesthem all the time.

But İt'This means that they can become addicted withover time.

This situation is very dangereous.,

Bbecause then they don't want to dofulfil their dutyies such as doing homework, going to school, or help youing their parents.

Additionally, they don't want to play real games with friends.

That's so children'seir social communication skills may weaken.

They feelt many emotions such as excitement, happiness and fear when they played video games.

The rest of your paragraph is in present tense, so this sentence should be in present as well!

So, they want to play video games all the time.

But İt'this means that they can become addicted with time.¶

Personally, I would combine the two sentences like this. I used different transition words to make it sound a little smoother.
"Because of this, they want to play video games all the time, which means that they can become addicted."

Because they don't want to do their dutytake care of their responsibilities, such as doing homework, going to school, help youand helping their parents.

First, I would combine the two sentences. "This situation is very dangerous, because they don't want to take care of their responsibilities, such as doing homework, going to school, and helping their parents."

I would use the word 'duty' for things you do at work. Things people do at home or in their personal lives I consider 'responsibilities'.
I changed the present tense verbs to present participle (-ing) because since they are the subject's responsibilities, they are continuous.

I changed helping your parents to helping their parents, because you used 'they' before.

Additionally, they don't want to play real games with friends.

That's soWith so much time spent playing video games, children's social communication skills may weaken.

Consequently, their parents should limit their time spent playing video games.

This is grammatically correct. But to make your writing sound smoother, I would combine the two sentences and use therefore instead of consequently.

"Children don't have a self-control mechanism, therefore, their parents should limit their time spent playing video games."