asweigart
A reader submitted this: I have had some problems with "four in the row"; it crashed at irregular intervals (for example, a 2 times 2 square of markers almost always crashed), and sometimes played worse than a beginner, actually selecting the worst possible move. Being a former programmer, I decided to investigate this, and found out that both problems had the same root -- the "worst fitness" is not -1, it is a far greater negative number (I saw at least -70 during my debug session). Changing the losing constant and the initial value in the computer move selection to, for example, -1000, seems to fix this issue.