I think studying a good, popular game will give you a lot of examples of difficult design decisions that you have to make.
For example, in World of Warcraft, Blizzard intentionally decided to make the classes unbalanced in 1 versus 1 player vs player combat (one person fighting another), but instead focused on making them balanced in larger groups (3v3, 5v5, and "battlegrounds" which is potentially up to 40 players on each side).
How do you make a large game environment that has a variety of environments but also feels like it's a part of a whole? How do you entice casual players to really get into the game and play for quite a while but also reward hardcore players for putting in lots of time? There are so many tradeoffs to make, and considering what an organization like Blizzard must have had to think about is a good exercise.
In Diablo3 it seems they still do not allow players to rotate the camera - I was very impressed by that. Another thing I noticed was how Diablo-a-like every single screen of that game already looks. Improved all over, but still every detail just cries out "Diablo".
Btw, I guess I won't buy that game. D2 was just too addicting for me. I completely lost half a year on that and I don't want that happen to me ever again.
For example, in World of Warcraft, Blizzard intentionally decided to make the classes unbalanced in 1 versus 1 player vs player combat (one person fighting another), but instead focused on making them balanced in larger groups (3v3, 5v5, and "battlegrounds" which is potentially up to 40 players on each side).
How do you make a large game environment that has a variety of environments but also feels like it's a part of a whole? How do you entice casual players to really get into the game and play for quite a while but also reward hardcore players for putting in lots of time? There are so many tradeoffs to make, and considering what an organization like Blizzard must have had to think about is a good exercise.