Yes, it means 500€ for one game.

It is not a dedicated usage specialized for casinos. We say prices like this.

In the supermarkets we say:

• “4 € le kilo de tomates”

And on the market place, it would be common (if not always) to hear prices announced like this:

• “2 euros le sac de pomme de terre! Deux euros! Qui veut de mes belles pommes de terre ? Allez soyez pas timides !”