In the following days, Pokemon GO fans will be greeted with an "under construction" message when they open their favorite app. The game, designed by American developer Niantic, is currently undergoing its biggest update ever as major changes including a "Raid Battle" feature are being put into place.

In an official statement published on June 19 on 'Pokemon GO's' official website, the software developer announced that all gyms will remain temporarily disabled while they put "exciting changes in motion."

Aside from the "Raid Battle" feature, the update will enable players to earn badges when they visit different gyms around the world. A new motivation system that basically runs on berries will also be introduced.

Niantic did not state when they will be able to complete this major overhaul, but they pointed out that the "Raid Battle" feature will become available "over the next few weeks."

The developer will first release a beta version which will only be available to players at specific gyms. In the next few days, more players from gyms around the world will gradually be invited to participate.

Raids were designed to encourage cooperative gameplay. With it, up to 20 players can form a group and work together in battling Raid Bosses. They will appear randomly in gyms and their presence will be announced by a large egg with a timer.

As soon as the clock strikes zero, the egg will hatch and a rare Pokemon will appear. The group will only have five minutes to defeat the monster.

Rare Pokemons are much harder to defeat but if the group succeeds, they have a chance of snagging the powerful monster and some new items such as Rare Candies, Golden Razz Berries, and two kinds of Technical Machines.

Rare Candies are mysterious treats that when used on Pokemons will turn into that monster's candy. Golden Razz Berries will increase a trainer's chances of catching a Pokemon encountered in the wild. They can also be given to a monster assigned to a gym to increase its motivation meter. Lastly, Technical Machines are items that will enable trainers to teach their monster with either a Fast or Charged attack.

Because raids are centered around gyms, group members need to be in the same area. Raids are public by default but can be adjusted to private. And in order to join a raid, trainers are required to possess another new item. Players will be given one raid pass every day, but additional ones can be purchased.

Aside from the update, Niantic is kicking off a huge event for the game's avid fans. The Pokemon GO Fest will be held in Chicago this July 22. Tickets began selling June 19, but Express reported that they were already sold out on the same day.