Because of my recent fascination with invasive species, I've decided to invade Attnam with regular giant mushrooms.
The thing that I noticed is, those mushrooms don't just randomly sprout out new ones. They grow according to a pattern.
If anyone knows
Conway's Game of Life, you should get the idea. I know Conway's Game of Life is also used as a basis for ADOM herbs. Basically, what it means is that cells "live" or "die" depending on how many cells surround them.
IVAN mushrooms don't follow regular Conway's Game of Life - they use a slightly modified version. To live, any mushroom has to have more than one, but less than six neighbours. In other words, mushrooms are generated only if the space they'd appear in fulfills this requirement (2-5 surrounding shrooms), otherwise, if a mushroom already exists in such a square, it may die over time.
Check for yourselves:
Kind of... interesting for a behaviour that plays such a minor role in the game, isn't it? Then again, it's what keeps giant mushrooms in reasonable numbers. Magic mushrooms are except, since they can teleport and levitate.