in / on the court

They play volleyball in / on the court.

They play volleyball on in the volleyball court.

Optilang, how about:

They are playing soccer in/on the field.

New2grammarOptilang, how about:

They are playing soccer in/on the field.

Either works for me.

But we play

tennis on a court
football on a pitch
golf on a course
basketball on a court

A: Where's Tiger?
B: You don't know? The game has started. He's in the course.

One last question, is the above OK?

If you are talking about Tiger Woods and golf there are a couple of mistakes.

Golf is a game/sport. We play the game of golf.

However, I would not say - the game has started - since there is more than one game - each player is in effect playing their own game.

If they are playing match play than you could say his match has started.

I would say, he has

optilangeach player is in effect playing their own game.

Good point!

Why do you use "on the court"? but not "in the court"?

Vincent, prepositions are very tricky and often don't follow strong rules that apply each time.

Can I say,

They play volleyball at the court.