Shouldn't that be:
if (bulletYs[i] == 0 && bulletXs[i] >= 0) {
Serial.println("BAD BULLET BOY!");
bulletYs[i] = 0;
bulletXs[i] = -1; // Mark this array element as empty
}
Shouldn't that be:
if (bulletYs[i] == 0 && bulletXs[i] >= 0) {
Serial.println("BAD BULLET BOY!");
bulletYs[i] = 0;
bulletXs[i] = -1; // Mark this array element as empty
}