Spør medspilleren eller motspilleren, for den saks skyld.

Spør is the imperative form of å spørre (to ask), so the sentence is a command or instruction: Ask ...

In Norwegian, just like in English, the subject is usually left out in commands. The understood subject is you.

• Spør medspilleren. = Ask the teammate.
• You do not normally need du here.

If you did add du, it would sound more marked or emphatic.

They are built from two very useful parts:

• med- = with
• mot- = against
• spiller = player

So:

• medspiller = teammate / fellow player / ally
• motspiller = opponent / opposing player / adversary

Depending on context, these words can be used not only in sports or games, but also more figuratively for people who are on your side or against you.

The -en ending marks the definite singular for many masculine nouns in Bokmål.

• en medspiller = a teammate

• medspilleren = the teammate

• en motspiller = an opponent
• motspilleren = the opponent

Norwegian often uses the definite form where English might or might not. Here it sounds like the speaker means the relevant teammate or opponent in the situation, not just any random one.

Because both medspilleren and motspilleren are objects of the same verb spør.

So the structure is simply:

• Spør X eller Y = Ask X or Y

Norwegian does not need to repeat the verb:

• Spør medspilleren eller motspilleren

just like English says:

• Ask the teammate or the opponent

It is an idiomatic expression meaning something like:

• for that matter
• if it comes to that
• come to think of it

Here it adds the idea that the second option is just as possible, or that the distinction is not very important.

So the sentence is not just saying ask one or the other. It also carries a nuance like:

• Ask the teammate — or the opponent, for that matter.

This is best learned as a fixed expression.

A rough breakdown is:

• for = for
• den = that
• saks = an old-style genitive form related to sak (matter / case)
• skyld = sake

So very literally, it is something like for that matter's sake. But that literal analysis is not how learners should try to build new phrases. In modern Norwegian, this expression is basically a set idiom.

So the safest approach is:

• learn for den saks skyld as a whole
• understand it as for that matter

Not really.

Skyld can mean guilt / blame / fault in some contexts, but in expressions with for ... skyld, it often means for the sake of.

Examples:

• for moro skyld = for fun
• for ordens skyld = for the sake of order / just to be clear
• for den saks skyld = for that matter

So in this sentence, skyld is not about guilt at all.

Because for den saks skyld works like a parenthetical comment added onto the main sentence.

The main command is:

• Spør medspilleren eller motspilleren

Then the speaker adds:

• for den saks skyld

The comma helps show that this last part is a side comment, much like in English:

• Ask the teammate or the opponent, for that matter.

It is a normal idiomatic expression, not something bizarre or obsolete. But it can sound a little more deliberate or rhetorical than very plain everyday wording.

You will hear it in both speech and writing, especially when someone wants to add a by the way, that also applies kind of nuance.

So it is perfectly natural, but it is also slightly more expressive than just stopping after motspilleren.