Learn Hardcore Russian: Новое открытие радует меня.

Because открытие is a neuter noun in the nominative case. Adjectives in Russian must agree with the noun they modify in gender, number, and case. The neuter singular nominative form of новый is новое, so we say новое открытие.

What case is открытие in, and how do you know?

Открытие is in the nominative case because it functions as the subject of the sentence—it is “what” performs the action (it pleases). In Russian, the subject of a clause is normally in the nominative.

What does the verb радует mean, and why is it used here?

Радует is the 3rd person singular present form of радовать, which literally means “to make someone happy” or “to please.” The sentence literally reads “The new discovery pleases me.” It’s a transitive verb taking a direct object (the person who is pleased).

Why is меня used instead of мне in this sentence?

Меня is the accusative case form of я, used after verbs like радовать that take a direct object in the accusative. Although меня looks identical to the genitive, here it is functioning as the accusative object.

Could I say ? Would that change the meaning?