To celebrate the 20th anniversary of Diablo, Blizzard will be holding a special in-game event in the Diablo game but that is not the only game that has an event. The other Blizzard games like Heroes of the Storm, Hearthstone, Overwatch and StarCraft II will all have an event of their own.
If you play Diablo III, the in-game event, The Darkening of Tristram will let the player explore the reimagine version of the cathedral in the first game. They can also pick up some familiar items.
Heroes of the Storm player will get the chance to get the new Diablo-themed portrait in the new brawl map. Hearthstone players can take part in the Tavern Brawl where they will have to play a new hooded stranger with a grim deck.
Overwatch players will get in-game sprays to represent their favorite class in Diablo III. There is also a new player icon modeled after the Lord of Terror. StarCarft II players will get a Diablo-themed worker portrait. World of Warcraft will also have an in-game event for the celebration.