Galaxea

Two of the three dice are the sides of a rectangle — and the game is which two, and where to hang it.

The Galaxea board

Play Galaxea

Grades
3–6
Subjects
Shapes & Space, Multiplying & Dividing, Adding & Subtracting
Kind
Two-player game
Cost
Free, no account, no ads

What it is

Two corals grow on a grid of dots. Roll three dice, tap two of them, and those are the sides of a rectangle that hangs off a corner of your own coral and grows diagonally outwards. Open water scores nothing: the water covered twice is the score, so the reef you want is the one drawn across your rival’s.

What it gives you to practise

Area as multiplication, chosen rather than computed. The arithmetic is in deciding which two of three dice to spend and where to hang what they make — and the third die, the one you did not use, is part of that decision. Lines may cross but may never run along each other, which quietly limits where a corner can go.

In a classroom

Gordon Hamilton, MathPickle. Three reefs to play against, a hot seat for two on one tablet, and an online room. It was the first two-player game we published, and it is still the quickest of them to explain.

The rules

Two corals grow on a grid of dots, and every rectangle is a multiplication fact you rolled. The water covered twice is the score.

Tap two dice — they are the sides of your rectangle, and it hangs on a corner of your own coral.

You score nothing for open water: draw across the other coral and the overlap is shaded yours.

A corner grows one way only — diagonally outwards — because lines may cross but may never run along each other.

Play Galaxea

Near it on the shelf