Hoarfrost

Grow a snow crystal from a single frozen cell. Vapour drifts between the cells of a hexagonal grid, the edge of the ice catches it, and two numbers decide whether you get a plate, a star or a fern.

Keys: Space pauses and resumes, N steps, R restarts.

Crystal

Changes to the parameters restart the crystal.

Second stage

A falling snowflake passes through layers of different air. Here the crystal switches to a second β and γ once it has grown the chosen share of the way to the edge.

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