tiimusen no sukoa, takai zyan.

チーム戦 means a team match, team battle, or team-based competition.

It is made from:

• チーム = team
• 戦（せん） = match / battle / contest

So チーム戦のスコア means something like the score in the team match or the team-match score.

Here, の connects two nouns.

• チーム戦 = team match
• スコア = score

So チーム戦のスコア means:

• the score of the team match
• the score for the team event
• the team-match score

This is a very common use of の in Japanese: noun + の + noun.

It often works like English of, 's, or an adjective-like noun modifier.

The comma shows a pause, and it helps split the sentence into two parts:

• チーム戦のスコア = the team-match score
• 高いじゃん = is high / wow, it's high

This kind of pause is very natural in casual speech. It gives the sentence a conversational feel, almost like:

• As for the team-match score... it's high, huh
• That team-match score... it's pretty high

The comma is not required in every situation, but it reflects how someone might naturally speak.

In casual Japanese, particles are often omitted when the meaning is clear.

A more fully marked version might be:

• チーム戦のスコアは高いじゃん。

Here, は would mark スコア as the topic.

But in casual spoken Japanese, leaving it out is very common:

• チーム戦のスコア、高いじゃん。

That sounds natural and conversational.

So the omitted particle is most likely something like は.

Because 高い is an い-adjective, and い-adjectives can function as predicates by themselves.

So:

• 高い = is high

You do not need だ after an い-adjective.

For example:

• 値段が高い。 = The price is high.
• スコアが高い。 = The score is high.

You could make it more polite with です:

• 高いです

But in this sentence, the style is casual, so 高い by itself is correct.

In Japanese, scores are commonly described as high or low, just like in English:

• スコアが高い = the score is high
• スコアが低い = the score is low

So 高い here does not mean physically tall or expensive. It means numerically high.

This is very normal Japanese.

じゃん is a very casual sentence-ending expression. It often adds a feeling like:

• you know
• see?
• right?
• wow, it is
• look at that

In this sentence, 高いじゃん suggests something like:

• It’s high, isn’t it?
• Wow, that score is high.
• See? The score is high.

It often expresses:

• surprise
• emphasis
• pointing something out
• seeking agreement

Even though じゃん comes historically from じゃない, here it is not actually negative.

They are related, but they are not always used the same way.

In casual modern speech, sentence-final じゃん often works as a soft emphatic ending. It can mean something like:

• isn’t it
• see
• come on, it’s...
• look, it’s...

So:

• 高いじゃん。

does not mean it isn’t high.
It means something closer to:

• It’s high, isn’t it?
• That’s pretty high!

This is one of those cases where the historical form looks negative, but the actual meaning in conversation is not negative.

Yes, very casual.

Reasons:

• スコア is fine in any register, but the overall phrasing is conversational.
• The particle after スコア is omitted.
• じゃん is distinctly casual.
• There is no polite ending like です or ですね.

This would sound natural among friends, classmates, teammates, or in informal conversation.

It would be less suitable in very formal contexts.

Yes. Some possible versions are:

• チーム戦のスコアは高い。
  = The team-match score is high.

• チーム戦のスコアは高いじゃん。
  = The team-match score is high, isn’t it?

• チーム戦のスコア、高いね。
  = That team-match score is high, huh.

The original sentence is just a more casual, spoken-style version.

It sounds like the speaker has just noticed the score or is pointing it out to someone else.

Depending on tone, it can feel like:

• mild surprise
• admiration
• casual observation
• trying to get the listener to agree

So it may feel like:

• Wow, the team-match score is pretty high.
• That team-match score is high, isn’t it?
• See? The team-match score is high.

The exact nuance depends a lot on intonation, but the overall feeling is informal and reactive.