Behind the scenes of Hearthstone innovations: Tavern Brawls, card backs, cute doggo Nimbus mascot and more

The Hearthstone team revealed some projects that were made during their pre-holiday hack-a-thon events. 

As a tradition, the Free Your Mind event involves Team 5 members working on passion projects before the start of a new year. This is done in either a group or individually. These projects just have to be linked to Hearthstone.

Some of these projects made it into the game that players experience today. For instance, when Hearthstone players visit their collection manager, they can choose to equip a random card back. Thanks to Free Your Mind projects, players can also copy and paste deck codes into the game, re-order their decks, as well as have their golden cards appear while drafting decks in Arena mode. 

The parties in Hearthstone Battlegrounds were also born from these hack-a-thon projects. Additionally, players can go into their collection and search for dust refunds thanks to Free Your Mind.     

Although several projects improved the game’s systems and tools, not all of them made it into the live server.

The Hearthstone team revealed projects such as Tavern Brawls that played like a rhythm game, a dating sim and one that paid tribute to StarCraft. At one time, a StarCraft card set was even presented during a pre-holiday hack-a-thon.

“There are also a few projects that are being considered for the live game that are not quite ready to be shared yet,” the Hearthstone team added. 

Just last year, Lead Designer Pat Nagle helped with a project that involved simulations, artificial intelligence (AI) and machine learning. This project simulated a Hearthstone competition where computers played 32 submitted deck lists. Best-of-three matches were played in the tournament.

This was followed up by best-of-five semifinal games and best-of-seven matches in the grand finals. In total, the AI ended up making 8,253 decisions. The winning deck was Highlander Hunter, which was submitted by Madness at the Darkmoon Faire Design Lead John Mcintyre.

Here's the winning Highlander Hunter deck code:

This tournament inspired the Fairy Tales Tavern Brawl, which involved players becoming the Headless Horseman and directing their own production within Hearthstone. 

“This was one implementation of the machine learning AI, which the team plans to improve for potential use in the future,” the Hearthstone team added.

Also in 2020, Senior Test Analyst David Carlock from Quality Assurance wanted to create a Hearthstone card back dedicated to his dog, Nimbus.

Nimbus visited the campus regularly and soon became Hearthstone’s unofficial mascot. Artist Juyoung Oh then helped Carlock create the final version of the Nimbus card back. 

Although this card back isn't in the game, the Hearthstone team noted that Nimbus is nonetheless important and inspirational as an unofficial game mascot.