How can tennis be real if our eyes aren't real?

Real tennis vs complex tennis

Quaternion tennis

This seems made up, like a game you’d read about or see in some b-rated sci-if film.

The Tennis Court Oath from the French Revolution was declared in such a tennis court.

Before I learned that, I always wondered why they would go to a tennis court, as opposed to a square or just on the street. Turns out they preferred a roof.

Fancy a game?

They play this in Ever After