long last_line = 0;
ifstream gamelog("example_gamelog_name.txt"); // gamelog names do change, your gonna have to generate the correct names
if (gamelog.is_open()) {
  std::string line;
  gamelog.seekg (last_line, ios::beg); // puts it back to the last read position
  while (!gamelog.eof()) { // reads until the end of file is reached
    getline(gamelog,line); // saves a line into a string 'line' to do with as you wish
  }
  gamelog.seekg(0, ios::end); // sets the pointer to the last point in the file
  last_line = gamelog.tellg(); // saves the last point into the variable 'last_line'
} else {
  printf("Error occured, gamelog unreadable.\n");
}