TL;DW (credit to /u/sydien) Reaper of Souls was originally going to be released Nov. 2013 When Mosquiera took over, the team wanted to refocus on Fantasy, Endgame for Everyone, Make Online Matter. Sales projected 6.6 million sold in the first year, which was done in the first week. Mistake - They stuck to the structure of D2, scaling difficulty in the same repeated story Mosquiera's first legendary was after 104 hours and it was a quiver for his barbarian. Medieval Ebay short circuited the reward loop. Launch was the lowest point of morale for the D3 team. Mistake - They misunderstood the player psychology. They tried to design a game that would be played for 10 years leading to very stingy loot drops. Mistake - They thought players wanted a hard game, but players wanted a feeling of achievement instead. Mistake - They thought randomness was the key to Diablo. Mistake - Wrong type of beta: too short, mostly a demo, no end game testing. Part II Console version was built from the ground up. Port was a bad word. Console development gave them an opportunity to analyze the design philosophy behind the PC version. A controversial issue was the controller vs. mouse/keyboard. The controller gave an intimate connection with the player avatar. Console development led to the creation of adventure mode. At D3 launch, monsters were hardcoded with certain stats based on where they spawned. The requirement for less to be on the console screen led to Loot 2.0 Fixed - Tied power directly to rarity, a change from the arbitrary values at launch A constant discussion was had around "That's not in D2, why should it be in D3" As RoS development continued, developers realized they were solving the symptoms of D3 Vanilla and not the root problem, i.e. loot scarcity. Legendaries were originally made as "piles of stats" because they were limited on time. The intention of the AH was to provide a safe place to trade. D2 was plagued by account compromises of all sorts. Originally they believed the AH would be used by 10% of the playerbase. The catalyst for the AH removal started with some backend updates to their commerce systems regarding Hearthstone and Heroes of the Storm They had developed multiple systems to "fix" the AH, but within twenty minutes of discussing the AH removal the entire leadership was on board. Part III Lessons Learned - Focus on the pillars of your game design. It's important that a developer be able to express to someone the pure DNA of their game. Lessons Learned - Know your fears For D3's team, the two fears were: "That's not Diablo" living up to the legacy of D2, and "Afraid to be too generous" in a loot based game. Now they believe that it's better if you get all the loot and leave the game happy rather than get nothing and leave frustrated. Lessons Learned - Randomness is not replayability. Lessons Learned - Remember the Fantasy, constantly ask "why does this matter for the player?" Lessons Learned - Its your team that defines success, not sales or critic reviews. Question: How did a relatively new guy become game director? -- Mosquiera, "I don't know. I wasn't originally going to apply for the Game Director job. I looked out at the team and wanted to keep them together and that's why I applied." Question: Do you think it's better to engage people early on with game development or to do the bulk of the work and then do a test? Mosquiera, "The earlier we get feedback the better." Question: After the difficulty structure change, did the D3 team encounter difficulty changing people's perception of what each level of difficulty meant. "Yes." Question: Are there plans to unify PC and console? "There are many challenges in doing so. Underneath the hood of the games, they are actually very different, but they're going to do a better job of keeping both versions in teh same update." Question: Is there a future for a playerbase trading system in D3? "No. Fundamental belief that trading undermines the core design of a loot based game." That's it. Lots of this is paraphrased, but those were the highlights. Good talk if you have time to watch it.