Pokémon Go players around the world will be able to watch the happenings at Pokémon Go Fest in Chicago this weekend (22 July), as well as participating in the global event running concurrently with the ticketed event in the US.

Developer Niantic has announced a partnership with streaming service Twitch, but what exactly will be streamed remains a mystery. Video and recording equipment are banned at the event, so this will be the only authorised look inside the event.

Last week Niantic revealed how the world will come together to play the hit augmented reality mobile game at the weekend.

Players at Pokémon Go Fest in Chicago will determine a bonus reward affecting players worldwide during set windows.

Those playing outside the event will, at the same time, be able to determine the duration during which any bonus bestows them with additional XP, Pokémon candy, stardust or other gameplay bonuses.

Which bonus is chosen will be determined by the number of a particular type of Pokémon people decide to capture (fire, water etc) with the number of Pokémon caught worldwide determining whether a Mystery Challenge is unlocked.

This challenge involves only players in Chicago, and should they complete it a reward will be unlocked for players around the world. This reward will be active until Monday 24 July.

Nobody outside Niantic knows what this entails, but we suspect it'll involve the legendary Pokémon that have so far eluded players.

Eleven legendary Pokémon currently exist in the game but have not yet been made available to capture. These are legendary birds Articuno, Zapdos and Moltres, plus Mewtwo and Mew from the first generation of Pokémon.

From the second generation of monsters are legendary dogs Entei, Raikou and Suicune, plus Lugia, Ho-Oh and Celebi.

Pokémon Go Fest and the wider event will run from 10am to 7pm Chicago time. That's 4pm to 1am UK time.

Pokemon Go Raids and Gyms
Artwork from a recent Pokémon Go update changing gyms and introducing Raids. The Pokémon Company