A Dobble card looks like this (modulo copyrighted images)

Each card has eight symbols on it

Any two cards have exactly one symbol in common

- You can place all the cards containing a given symbol on a line.
- There is a unique line containing each pair of cards.
- Eight lines intersect at a single card.

It's a projective plane!

Cards are points and lines correspond to symbols.

A simpler example

A projective plane is its own dual - you can swap points and lines and it still has the same structure.

You can replace the symbols on a Dobble card with more Dobble cards.

It still works!

There's absolutely no reason why you shouldn't keep going.

Ta!

Generate your own: christianp.github.io/droste-dobble

Icons from Emoji One (CC-BY-SA)