Help with 8x8 LED matrix and MAX7219 code Conway's Game of Life (almost done)

Using Arduino LEDs and Multiplexing
2

My first recommendation would be to use 'unsigned char' instead of 'int' for each element of the arrays:

unsigned char world1[8][8] = {{0, 0, 0, 1, 0, 0, 0, 0},
                    {0, 0, 1, 0, 1, 0, 0, 0},
                    {0, 1, 0, 1, 1, 0, 0, 0},
                    {1, 0, 1, 0, 0, 1, 1, 0},
                    {0, 1, 1, 0, 0, 1, 0, 1},
                    {0, 0, 0, 1, 1, 0, 1, 0},
                    {0, 0, 0, 1, 0, 1, 0, 0},
                    {0, 0, 0, 0, 1, 0, 0, 0}};
unsigned char world2[8][8];

This will save 50% of the memory space.