The game basically is like a card draft. you are playing to purchase available cards from several decks. As you purchase cards they are added to your discard pile. once you have gone through your deck you shuffle your discard and it again becomes your deck. So your purchased cards are now available for play at this point. The thing here is you need to purchase victory cards as well which do little to nothing for actual game play. It is not until end game that they have any use. End game comes when three stacks of cards have been depleted or the stack of highest value victory cards has been depleted.
Once you are going your have two basic actions. Play an action card which will always be one of the purchased cards from a past round. Secondly you can purchase a new card. There are cards that add more actions, allow you to make more purchases, give you card draws and more specific actions. The cool part about this is you are always holding a hand of cards so players are allowed to look at their cards and figure out what they are going to do while other people are acting. This allows for very fast play once the game is going. Or very slow! I saw someone build a deck that focused on actions and drawing cards, which caused his turn to be a bit long.
I am pretty enthusiastic for the game, but I don't think I have ever won. This is a problem with six players and my style. If you are doing six players you really need to extend the end game conditions. The game goes very fast otherwise. My style is to see combinations that work but over a long term. I go after the cards i need and get many of them. I think I would be better served to only get a few cards of any given type and then focus on actions and card draws to speed up how my evil plan completes.
One sort of bad thing I noticed is a few negative cards can drive the game. This happened with the thief card. I basically decided to play without coins because of this. There is a card out of the intrigue set that similarly dictated play. Perhaps because I was playing with eight in my deck. Another bad point is you can drop a load of cash on the game as there are tons of expansions.