Niemand darf beim Spiel betrügen.

This is because German is using a modal verb here.

• dürfen = a modal verb
• betrügen = the main action verb

In a normal main clause, German puts the finite verb in second position. Here, the finite verb is darf.

So the pattern is:

• Niemand
  • darf
    • ... + betrügen

The main verb betrügen stays in the infinitive and goes to the end of the clause.

This is very common in German:

• Ich kann Deutsch sprechen.
• Sie muss heute arbeiten.
• Niemand darf beim Spiel betrügen.

Here, dürfen expresses permission or what is allowed.

So Niemand darf ... means:

• Nobody is allowed to ...
• No one may ...

In this sentence, it creates a rule or prohibition.

That is slightly different from English can, which often means ability. German usually keeps those ideas more separate:

• dürfen = to be allowed to
• können = to be able to

So this sentence is about permission/rules, not ability.

Because Niemand is grammatically treated as singular.

Even though it refers to zero people, German uses a singular verb with it:

• Niemand ist da.
• Niemand weiß das.
• Niemand darf beim Spiel betrügen.

So darf is the correct 3rd person singular form of dürfen.

Niemand is an indefinite pronoun meaning no one or nobody.

It works like a subject by itself, so you do not need an article with it.

Compare:

• Der Mann = the man
• Jemand = someone
• Niemand = no one

So Niemand already contains the whole idea of no person.

beim is a contraction of:

• bei dem → beim

This is very common in German.

Here:

• bei takes the dative case
• dem is the dative form of das
• bei dem Spiel becomes beim Spiel

In this sentence, beim Spiel means something like:

• during the game
• in the game
• when playing

So beim is not a separate vocabulary item you have to memorize completely on its own; it is a very common shortened form of bei dem.

Both are possible in German, but they do not mean exactly the same thing.

• beim Spiel = during the game / while playing / in the context of the game
• im Spiel = in the game more literally, often meaning inside the game situation itself, and sometimes used in more abstract ways too

With betrügen, beim Spiel sounds very natural for cheating while playing.

So this sentence is focusing on the activity or situation of playing, not just physical or abstract location.

Because all German nouns are capitalized.

Here, Spiel is a noun meaning game or play, so it must begin with a capital letter.

Examples:

• das Spiel
• der Spieler
• die Regel

This is one of the most noticeable spelling rules in German.

No. betrügen can also mean to deceive or to cheat someone more generally.

For example, depending on context, it can refer to:

• cheating in a game
• cheating in business
• cheating a person
• even cheating on a partner

But in this sentence, because of beim Spiel, the meaning is clearly to cheat in a game.

So the context tells you which sense is meant.

Because here betrügen is being used intransitively in the sense of to cheat.

German can use betrügen in different ways:

• jemanden betrügen = to deceive/cheat someone
• beim Spiel betrügen = to cheat while playing

So in this sentence, the important idea is the action of cheating itself, not who is being cheated.

Not with the same meaning.

• Niemand darf beim Spiel betrügen. = Nobody is allowed to cheat in the game.
• Man darf beim Spiel nicht betrügen. = One is not allowed to cheat in the game / You must not cheat in the game.

These are close in meaning, but they are structured differently:

• Niemand focuses on no person
• man ... nicht gives a more general rule

Both are natural, but Niemand darf ... sounds a little more direct and emphatic.

It can depend on context.

• beim Spiel literally contains dem Spiel, which looks singular
• but German often uses this kind of phrase more generally too

So it could mean:

• during a specific game that has already been mentioned
• in game-playing / in the game situation more generally

If the sentence appears by itself, many learners might expect a specific game, but in practice German often uses this structure in general statements as well, especially if the situation is already clear from context.