Updating array in a function causes pointer lose - c

Question

I am trying to divide my code into functions, I have a sample code of "Game Of Life".
However, when I try to initialize 2D grid array in a function, gnuplot gives no valid data points error.
These are global variables declared before main:
static char **currWorld=NULL, **nextWorld=NULL
This is the original logic to init game grid, but this part is in main.
if (game == 0){ // Use Random input
for(i=1;i<nx-1;i++){
for(j=1;j<ny-1;j++) {
currWorld[i][j] = (real_rand() < prob);
population[w_plot] += currWorld[i][j];
}
}
}
else if (game == 1){ // Block, still life
printf("2x2 Block, still life\n");
int nx2 = nx/2;
int ny2 = ny/2;
currWorld[nx2+1][ny2+1] = currWorld[nx2][ny2+1] = currWorld[nx2+1][ny2] = currWorld[nx2][ny2] = 1;
population[w_plot] = 4;
}
else if (game == 2){ // Glider (spaceship)
printf("Glider (spaceship)\n");
// Your code codes here
}
else {
printf("Unknown game %d\n",game);
exit(-1);
}
This is my function:
int init_game(int choice, int probability){
int i,j;
if (choice == 0){ // Use Random input
for(i=1;i<nx-1;i++){
for(j=1;j<ny-1;j++) {
currWorld[i][j] = (real_rand() < probability);
population[w_plot] += currWorld[i][j];
}
}
}
else if (choice == 1){ // Block, still life
printf("2x2 Block, still life\n");
int nx2 = nx/2;
int ny2 = ny/2;
currWorld[nx2+1][ny2+1] = currWorld[nx2][ny2+1] = currWorld[nx2+1][ny2] = currWorld[nx2][ny2] = 1;
population[w_plot] = 4;
}
else if (choice == 2){ // Glider (spaceship)
printf("Glider (spaceship)\n");
// Your code codes here
}
else {
printf("Unknown game %d\n",choice);
exit(-1);
}
}
and my function call in main:
init_game(game, prob);
value of game is 0, prob is 0.2 and I tested memory allocations and other stuff, they work fine.
Only difference is I moved the logic to a function. How can this happen? My arrays are global, I cannot understand how it cannot be initialized.
This is the gnuplot error:
Skipping data file with no valid points
Since gnuplot and other functions are works fine, I did not add them but if you need any info, I can add.
Here is the link of file itself:
file