Hearthstone is Blizzard Entertainment's digital card game, released in 2014 and set in the Warcraft universe, and games are framed as matches in a cosy tavern run by the Innkeeper, Harth Stonebrew. His voiced greetings and reactions punctuate menus, openings and pack reveals, so short exclamations like this ooh were clipped by players and shared on soundboards and in videos. It stayed popular because it needs no context — one warm, amazed noise that Hearthstone fans recognise instantly and other viewers still understand as delighted surprise.