Empires has Duration cards, which previously appeared in Dominion: Seaside and Dominion: Adventures; Events, which previously appeared in Dominion: Adventures; and cards using VP tokens, which previously appeared in Dominion: Prosperity.
Duration cards are orange, and have abilities that affect future turns. Duration cards are not discarded in Clean-up if they have something left to do; they stay in play until the Clean-up of the last turn that they do something.
Additionally, if a card such as Throne Room plays a Duration card multiple times, that card also stays in play until the Duration card leaves play, to track the fact that the Duration card was played multiple times.
Players should keep track of whether or not a Duration card was played on the current turn, such as by putting their cards into two lines (older cards and this turn's cards).
Events are not Kingdom cards. In a player's Buy phase, when a player can buy a card, they can buy an Event instead. Buying an Event means paying the cost indicated on the Event and then doing the effect of the Event.
The Event just stays on the table, the player does not take it; there is no way for players to gain one or end up with one in their decks. Buying an Event uses up a Buy; normally a player can either buy a card, or buy an Event.
A player with two Buys, such as after playing Villa, could buy two cards, or buy two Events, or buy a card and an Event (in either order). The same Event can be bought multiple times in a turn if the player has the Buys and available to do it.
Players cannot play further Treasures that turn after buying an Event. Buying an Event is not buying a card and so does not trigger cards like Charm. Costs of Events are not affected by cards like Bridge (from Dominion: Intrigue).
Victory Point tokens () are simply tokens that are worth at the end of the game. They provide a way to score that does not appear in a player's deck. They come in 1, 2, and 5 amounts; make change as needed. They are not counter-limited; use a replacement if you run out.
Cards say "+1" (or other amounts) to indicate that a player takes a token or tokens. Cards that give + or "add" tokens to a pile take the tokens from the pile of unused tokens, not from a player. tokens are not private; anyone can count them.
A few Action cards have the type Gathering; this has no special functionality, but groups cards that add tokens to their Supply pile. tokens on a pile stay there until an ability specifically removes them; when gaining a card from that pile, slide the tokens off onto the next card. tokens can be on a pile even if no cards are left in the pile (players may use the randomizer cards to mark them).