I quite enjoyed this talk, especially after having played Hearthstone obsessively for a biref period of time.
Personally, the two of the biggest takeaways from the talk were:
1. Stakes in the Ground
I like this idea of having certain objectives or ideals that help to anchor a project during development. Seems obvious, but I think it really helps to steer the game toward an intended direction.
2. Emotional Design
I thought the card which initially stole cards from the opponent’s deck was a great example. It was a card that felt good to play, but also ultimately too negative for the opponent on the receiving end. Finally, instead of stealing cards, the card was modified to copy cards instead. (Also an example of embracing the digital medium!)