These fill a number of roles. Card play can shift the balance of power rapidly. Players can only buy four cards at a time, and only for commanders in play. Like the new avenues of movement, cards open up the board by making no position impregnable, no attack a certainty. With cards in use, the game is more fluid and positions are constantly shifting. There is a separate deck of cards for each type of commander. Perhaps the most devastating card attacks are enabled by the nuclear commander: Playing a nuclear card has the potential to destroy all the armies on an entire continent. Energy also has a strategic importance. It is used to buy cards, to bring commanders and space stations into play, to bid for the most advantageous place in the turn order, and to play certain cards. Each round, players bid energy for the right to choose when they want to take their turns. But players who spend too much energy one turn may find themselves playing at a disadvantage the next turn, or even for the rest of the game. "Risk 2210 A.D." includes a five-turn limit, although it is possible to play as in normal "Risk" with unlimited turns. Whoever controls the most territories (and bonuses) at the end of the fifth year wins. The game includes the necessary equipment and cards for playing the classic version of "Risk". A map of the original Risk board, which does not contain the US Pacific regions, and has different oceanic connections. In more recent game boards, the connection between East Africa and the Middle East has been removed. There is also a moon map board used in Risk 2210 A.D. Note: there does not appear to be a bridge between the Exiled States of America and Canada on the actual artwork. Territories available in the edition with are shown in quotes. Lunar territories (not pictured) are noted by an asterisk. North America South America Europe  Africa  Antarctica Asia  Australia US Pacific Asia Pacific Southern Atlantic Northern Atlantic Indian Cresinion Delphot Sajon Avalon Hill has released a number of expansions for the "2210 A.D." game. Used as Tournament awards, these expansions were originally available only to retailers and have not been released commercially. To date, there are four "official" expansions, under the name "Frontline". A number of unofficial expansions have also been created by fans, covering such themes as terrorism, aerial assault, zombies, Antarctica and Godstorm-style relics  A video game version of Risk 2210 A.D. called "Invade Earth" was created by Jonathan Crosmer using Java.