Learn Finnish: On kunkin pelaajan vuoro heittää noppaa. - It is each player's turn to roll the dice.

kunkin is the genitive form of kukin (each). In Finnish, when a pronoun has an attached particle like -kin, the case ending is inserted into the middle of the word, right before the particle. The base ku- takes the genitive ending -n to become kun-, and then -kin is added back on. It is in the genitive case here to match pelaajan (player's), giving us 'each player's'.

Why doesn't the sentence start with a word for 'It', since the English translation says 'It is...'?

Finnish doesn't use dummy subjects like 'it' for general situations, weather, or turns. Expressions like 'It is time to...' or 'It is a player's turn' simply start directly with the verb On (is).

Why is noppa (die/dice) in the partitive case (noppaa) in this sentence?

The verb heittää (to throw or roll) takes a partitive object here because rolling a die is an action that doesn't consume or permanently change the die. If you were throwing the die into the trash permanently, it could take a total object, but for rolling in a game, you always use the partitive.

Is it possible to change the word order to pelaajan kunkin vuoro?