Learn Hardcore German: Die wichtigste Regel des Spiels ist einfach. - The most important rule of the game is simple.

In German, you form the superlative of an adjective either attributively by adding -ste plus any needed inflection (wichtig → wichtigste) or periphrastically in predicate position with am + adjective + -sten (e.g. “die Regel, die am wichtigsten ist”). You do not say mehr wichtig—mehr marks the comparative (wichtiger, “more important”).

Why is it die wichtigste Regel and not die wichtigste Regeln?

Regel (rule) is feminine and singular here. If you meant “rules” (plural), you would say Regeln. Since the sentence refers to one rule, it stays Regel.

What case is des Spiels and why is it used?

Des Spiels is the genitive singular of das Spiel. German uses the genitive to indicate possession or close relationship (“the rule of the game”). The article das becomes des, and the noun gets an -s.

Why does Spiels end with -s? And why no apostrophe?

Most masculine and neuter nouns in the genitive singular add -s or -es; Spiel (neuter) takes -s. German doesn’t use an apostrophe here (unlike English); you simply write des Spiels.

Could I say die wichtigste Regel vom Spiel instead of des Spiels?

You can say die wichtigste Regel vom Spiel (colloquial dative: von dem Spiel → vom Spiel), but it’s more wordy and less formal. The genitive (des Spiels) is more concise and preferred in writing.

Why is einfach at the end and not placed before ist?

German main clauses follow the V2 (verb-second) rule: the finite verb ist must be in second position, so modifiers or complements (like the predicate adjective einfach) come after the verb, often at the end.

Is einfach here an adjective or an adverb?

Here einfach is a predicate adjective describing Regel (“rule”). Predicate adjectives in German are not inflected, which is why it appears without an ending.

Could I use leicht instead of einfach? What’s the nuance?

Both can mean “easy,” but einfach stresses simplicity or lack of complexity (“not complicated”), whereas leicht focuses on ease of performance (“not difficult to do”). In many cases they’re interchangeable, though einfach fits stylistic emphasis on simplicity.