The applet below is a modification of the Game of Life applet, with exactly the same controls at the bottom and additional ones on the right. The latter allows one to define the birth (the left - B - column) and the survival (the right - S - column) rules. For example, if the boxes B1, B3, B5, S2, S5 are (the only ones that) checked, then an empty cell with 1, 3, or 5 neighbors will come to life in the next generation, while a live cell with either 2 or 5 neighbors will survive the upheaval of the transition rules' application. (Conway's original rules correspond to B3, S2 and S3 being checked.)