It seems there is more than meets the eye when it comes to Pokémon GO. Players are already mining through the game's code to discover its many secrets, and what they've uncovered so far is certainly going to be of interest to fans who can't get enough of the addictive mobile game.

For starters, fans have already discovered the existence of the three legendary bird Pokémon (Articuno, Zapdos and Moltres) in the game's code, though no players have yet discovered the elusive creatures in the real world. It's unclear if the rare Pokémon will even be available for capture in the wild, or if they might be tied to some yet-to-be-announced in-game event.

However, the discovery of some of the original Pokémon's most powerful creatures is just the start. Fans have also discovered additional types of berries (used for various Pokémon-hunting purposes), new types of incense (used to lure Pokémon to a location) and "natures" like stoic and raider, which are still a complete mystery. Natures usually refer to a Pokémon's personality type, but it remains to be seen how the system might be used in Pokémon GO.

One discovery that isn't much of a mystery is what appears to be a sponsorship with McDonald's. Pokémon GO developer Niantic has previously stated that it will be looking to add "sponsored locations" to the game, just as it did with Pokémon GO's predecessor Ingress.

Judging from files reportedly found within the game's code by one Reddit user, McDonald's is likely to be one of those key partnerships. The fast food company's name appears wholesale in the game code, and another redditor has seemingly discovered a McDonald's logo within the game files.

What does it mean? According to one of the people responsible for making the discovery, it appears that an in-game event may turn all McDonald's locations into gyms, though this is far from confirmed.

Businesses are already capitalizing on the Pokémon GO fever by promoting the game and encouraging players to visit. Even the National Park Service is using the game as a method to attract visitors. With all of that in mind, it makes perfect sense that major restaurant chains like McDonald's would seek to make an official deal with Niantic. McDonald's, for better or worse, is likely just the beginning.