Let me quote Liquipedia on the conquest format:
Brief description
[*]All matches will be best-of-5. The first player to win 3 games within the match is considered the winner of the match and advances.
[*]Each player must submit decklists from three unique classes prior to each stage of the event. Players may submit new decks prior to each stage of the event.
[*]A player must win one game with each of his three decks to win the match.
[*]When a player wins a game, the deck used by the winning player cannot be used for the remainder of the match.
[*]The losing player can keep the same deck used or switch to a different one of their choice.
[*]Players will be told what classes their opponent has available, but they won’t know which class is picked until both players have picked.
This system can be converted relatively easily to be used by aoe3. The only 'problematic' aspect that might need to be revised is that hearthstone has a functionality where you can easily hide what deck you selected, whereas in aoe3 this is visible. This could provide practical difficulties but should be something that can be overcome. This might ultimately provide a nice mix between the counterpick format and the mono-civ format. There's room to specialize in a handful of civs and try to understand the full spectrum of match ups (one of the goals of the mono-civ format), but it doesn't force people to pick civs that perform well in the meta.
I would really like to see a tournament hosted in this format some day. With this post I wanted to raise awareness and make people enthousiastic about the format. Just try to come up with a strategy as to which 3 civs you would like to pick. I feel like there's a lot of freedom to the point where you don't auto pick the 3 top civs but can also decide to go with some civs you are comfortable with and then add some complementary civs.
Thoughts? What would your civ strategy be? Would you like ESOC to host a tournament with this format?