Blizzard has confirmed next week's long-rumoured event celebrating the one-year anniversary of hit hero-based shooter Overwatch's release, as well as a new Game of the Year edition set to launch on 23 May.

From that same date until 12 June, all Overwatch players on PS4, Xbox One and PC can take part in the Anniversary Event, but Blizzard hasn't yet detailed what will be included.

New character skins, sprays and animations are a certainty given the leak last week of special themed Anniversary loot boxes, with reskinned maps, entirely new maps and new game modes also a distinct possibility.

Eager Overwatch fans digging into the game's public test realm (PTR) server dug up further details earlier in May. While things may have changed since then, they found evidence of between five and eight new items for each of the game's 24 heroes.

They also found encrypted files for three maps that could be new maps, reskinned maps or a mixture of the two.

Update: Blizzard has confirmed that three new Arena maps will be added to Overwatch on 23 May.

The Overwatch Game of the Year edition includes all the items from last year's Origins Edition: 10 loot boxes, hero skins and in-game items for fellow Blizzard titles Heroes of the Storm, World of Warcraft, Diablo 3 and StarCraft 2. You can see the detailed breakdown of what's included below.

Overwatch will also become free-to-play across all platforms for a whole weekend from Friday 26 May to Monday 29 May.

A video recapping the events of the game's first year has also been released, showing off all the new heroes, maps and live events that made Overwatch consistently successful over the past 12 months. That video is embedded at the top of this article.

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