A fire that burns down the whole town in a single tick

Fire, flood and plague spread from cell to cell, and the first version nearly always races across the whole map the moment it starts. The reason is subtle, and so is the fix that also makes the outcome repeatable. This entry shows it with a small burning town.

Why this works

Everything in a world should change at the same moment, from the same picture of how things stood. Reading the old picture and writing a new one stops news from outrunning time, so a front moves one step at a time.

When not to use it

Do not use it when you want a chain reaction that does cross the whole map at once, such as a bomb or lightning, or when spread should follow paths, like pipes or wires. For those, follow the links directly instead of cell by cell.

In the full entry

• What to build, step by step
• Starting values and the reason for each
• 3 common mistakes and the fix
• A diagram of every state
• 20 lines of example code with 4 checks that pass
• How your AI shows you that it works

Say this to your AI

Use the Spielerando entry "A fire that burns down the whole town in a single tick" (read_entry fire-spread-needs-two-grids) in my game. Build it step by step, and show me how you checked that it works.

Or skip this and connect the MCP: your AI then finds all of this by itself.Connect the MCP