Så vidt jeg vet, må vi gjette i bonusrunden.

Yes — it is very useful to learn så vidt jeg vet as a chunk. It means as far as I know and is used when the speaker wants to show limited certainty or avoid sounding too absolute.

In other words, the speaker is saying: this is what I believe, based on what I know.

No. Så vidt can mean different things depending on context.

In så vidt jeg vet, it means something like as far as.
But in other sentences, så vidt can mean barely / just:

• Jeg rakk så vidt bussen. = I just barely caught the bus.

So here, the whole expression så vidt jeg vet has an idiomatic meaning that is different from the barely meaning.

This is because Norwegian main clauses follow the V2 rule: the finite verb normally comes in the second position.

Here, Så vidt jeg vet takes the first position in the sentence. Because that first slot is already filled, the finite verb må comes next, before the subject vi:

• Så vidt jeg vet, må vi gjette i bonusrunden.

If you remove the introductory phrase, you get the more basic word order:

• Vi må gjette i bonusrunden.

Because jeg vet is inside the expression så vidt jeg vet, which behaves like a subordinate structure, where Norwegian usually keeps normal subject + verb order.

So:

• jeg vet = subject + verb

But the main clause still follows the V2 rule, which gives:

• må vi

So the sentence contains two different word-order patterns at the same time.

Because gjette comes after the modal verb må. After modal verbs in Norwegian, you normally use the bare infinitive, without å.

So you say:

• må gjette
• kan gjette
• skal gjette
• vil gjette

Not:

• må å gjette

It is the infinitive form of the verb å gjette.

You can think of it as the dictionary form of the verb. After må, Norwegian uses that infinitive directly:

• må gjette = must guess / have to guess

For comparison:

• å gjette = to guess
• gjetter = guess / am guessing / are guessing
• gjettet = guessed / guessed (past participle, depending on context)

Må expresses necessity, obligation, or something that is required.

In this sentence, it means that we have to guess or we must guess. It does not mean ability (can) or simple future (will).

So må is the right choice when something is necessary because of rules, circumstances, or logic.

Norwegian mainly distinguishes between vite and kjenne.

• vite = know a fact, know information
• kjenne = know a person, place, or something through familiarity

Since this sentence is about what the speaker knows as information, vet is correct:

• Så vidt jeg vet = as far as I know

You would not use kjenner here.

Because Norwegian normally writes compound nouns as one word.

Here the base noun is:

• bonusrunde = bonus round

Then the definite singular ending -en is added:

• bonusrunden = the bonus round

This is very typical in Norwegian. English often separates these words, but Norwegian usually joins them.

It marks the noun as definite singular.

So:

• en bonusrunde = a bonus round
• bonusrunden = the bonus round

Norwegian often puts definiteness at the end of the noun instead of using a separate word like the.

Here i means in or during, and it is the natural preposition for being within a round or phase of something.

So i bonusrunden means in the bonus round or during the bonus round.

This is the usual way to talk about something happening within a game round, stage, or period.

The comma separates the introductory comment from the main statement.

Så vidt jeg vet is a kind of hedge — it tells you that the speaker is not claiming complete certainty. The comma helps show that this part is a separate comment on the rest of the sentence.

It also matches a natural pause in speech.