Tetracrystals of Veluria

A toy for growing crystals, with a two-player contest added. Plant seeds or monads in up to eight colours on a 16 x 16 grid of water, then let the sun shine. Each generation every crystal grows one stage, from seed to monad to tetrad to shell, and then melts back to water. A tetrad sprouts up to four new seeds of its colour at right angles, but only on open water, out of the shadow of other tetrads and shells, and within the grid. Set the sun's speed, freeze, step one generation, scatter random seeds or turn on TRACE so melted crystals leave a mark. In the two-player game each player picks a colour and plants three crystals; the colour that wipes out the other wins, and a stalemate after 300 generations is a tie.

Controls: Use either controller. In planting, the stick moves the box over the grid, the left button plants the type and colour shown, and the right button switches to the menu (stick up and down to pick, left and right to change). While growing, the menu sets the sun's speed, freezes, steps and adds seeds. The keypad offers shortcuts, but everything can be done with the stick.

ColecoVision version credited in the source to Claude (an AI made by Anthropic) for Amy Studio, in Amy, the language by Amy Bienvenu, 2026: a reimagined adaptation of the published rules. From COMPUTE!'s Gazette, January 1984, page 86: original Commodore 64 program by Todd Heimarck. This is a modern homebrew adaptation, not a commercial Coleco release.