Maybe the first Agent-Based Model. T.C. Schelling, “Dynamic Models of Segregation”, Journal of Mathematical Sociology 1, 143–186 (1971), Micromotives and Macrobehavior (WW Norton, 1978).
No computers. Schelling worked the model on a checkerboard.
Vary %-similar-wanted and the density of turtles on the patches.
Add the following to the procedure
to update-turtles, after
ifelse happy? [ set shape "square" ] [ set shape "square-x" ]