Use rock-paper-scissors to determine who goes first — winner get to choose whether to go first or second. At the start of the game, the player who will go first is dealt six cards, and the player who will go second is dealt eight cards. Players then alternate taking turns, with each turn having five phases: Draw, Upgrade, Deploy, Attack, and Discard.
At the start of his or her turn, the player will draw as many cards as necessary to bring the total in their hand to six. Note that the player who starts second only has eight cards at the very start of the game, a one time benefit meant to compensate for the disadvantage of going second. From the very first turn that player only draws to restore his hand to six cards.
A player cannot play an anytime card while drawing. All cards must be drawn at once. However, a player can play one or more anytime cards right before or right after drawing.
When a player must draw, but there are no cards available, the discard pile is shuffled and becomes the new deck from which to draw. Note that the discard pile is not shuffled until the moment that a card must be drawn but is not available.
The player can add one upgrade from his hand to each ship he or she has in play. Different ships have different maximum numbers of upgrades: Jacks (destroyers) can have two upgrades, Queens (cruisers) can have three, and Kings (dreadnaughts) can have four. No ship can have more than one upgrade of the same type. For example, a King (dreadnaught) could have a 2, 6, 8 and 9 but could not have 2, 6, 8, and another 8.
Upgrades improve the ships to which they're applied by raising their defense value and sometimes their attack value. The 3, 6, 7, 8, and 9 upgrades all work the same way, by raising the attack value and defense value of the ship by one. The 2 (shield) upgrade works differently, only raising the defense value by one, but also protecting the ship from megamissiles and megamissile barrages.
During this phase, if the player has a ship card in his hand he may put it in play by laying face up in front of him or her. It will have attack and defense values of zero, and thus will be vulnerable to an opponent's 4 (cloaked mine) card until it is upgraded.
If the player has both an upgrade and an Ace (time travel commandos) in his hand, the Ace can be played now to allow the newly deployed ship to take an upgrade. Similarly, if the player has both another ship card and an Ace (time travel commandos) in his hand, the Ace can be played now to allow the second ship to be deployed. Playing an Ace at this time only allows an extra upgrade or an extra deployment, not both (unless the player has two Aces and uses them both).
It's time to do some damage! During the attack phase, the player announces which of his ships (if any) are attacking, and plays an attack card — meaning a 5 (megamissile) or 10 (megamissile barrage) — from his hand if he or she has one and wishes to use it.
Attack cards are resolved first. Note that when attacking a player can play a 5 or a 10 but not both and not more than one no matter how many are in his or her hand.
If the attack card is a 5 (megamissile) card, and the opponent has ships, he or she must declare which one of them (if any) is blocking the 5 (megamissile) attack. If this ship has a 2 (shield) upgrade, it only loses this upgrade, i.e., the 2 (shield) card (and only that card) is placed in the discard pile. If this ship does not have a 2 (shield) upgrade, it is destroyed, and it and all of its upgrades are placed in the discard pile.
If the attack card is a 5 (megamissile) card, and the opponent does not have any ships, or chooses not to have a ship block the attack, then his or her base takes one point of damage.
If the attack card is a 10 (megamissile barrage) card, and the opponent has ships, then all of his or her ships are affected as if they were hit by a 5 (megamissile) card. In other words, those with 2 (shield) upgrades lose them but are otherwise unharmed, and those without them are destroyed.
If the attack card is a 10 (megamissile barrage) card, and the opponent does not have any ships, his or her base takes three points of damage. Note that unlike with the 5 (megamissile) card, your opponent cannot choose to have his ships avoid this attack.
Note that your opponent may instantly negate your attack card with an Ace (time travel commandos) card if he or she has one in his or her hand and chooses to play it. If so, and you have an Ace (time travel commandos) card, you can use it to negate the first Ace, allowing the attack card to function normally.
Once the attack card, if any, is resolved, attacks from ships are resolved.
Ships have an attack value equal to the number of 3, 6, 7, 8, and 9 upgrades they have. If the opponent also has ships in play that weren't affected by an attack card, he or she can block attacks by declaring which ship is intercepting it. Ships can block any attack, even if it means they are destroyed in the process. Ships can withstand an attack value up to their defense value, which is the same as the number of upgrades, i.e., the number of 2, 3, 6, 7, 8, and 9 upgrades they have. If a ship blocks an attack and its defense value is equal to or more than the attacker's attack value, then the attack is blocked and the defending ship is unharmed. If a ship blocks an attack and its defense value is less than the attacker's attack value, then the attack is blocked and the defending ship is destroyed, and it and all its upgrades are placed in the discard pile.
For example, a player attacks with his King (dreadnaught) that has 3 (fighter squadron) and 8 (laser cannon) upgrades. This ship has an attack value of 2 because it has two upgrades and neither of them are the 2 (shield) upgrade. The opponent defends with his Queen (cruiser) that has 2 (shield) and 9 (antimatter torpedo launcher) upgrades. This ship has a defense value of 2 because it has two upgrades. The opponent's cruiser blocks the attack and is unharmed, because the attack value and the defense value are equal. If the attacking King (dreadnaught) had had one more upgrade, then the defending Queen (cruiser) would have been destroyed and it and all of its upgrade cards would have been placed in the discard pile.
If an attacking ship is not blocked, then the opponent's base takes as many points of damage as the ship's attack value. Note that as with the 5 (megamissile) attack card, a defending player with available ships can choose not to use them to block an attack and have his or her base take the damage instead.
Also, note that attacking ships are never harmed no matter how strong the ship used to block it may be.
After attacks are resolved, the player may discard as many cards as he or she wishes before ending his or her turn. The player may choose not to discard any, or may discard them all, or anywhere in between.
At any point, when you bring your opponent's base to zero (or fewer) points, and that player cannot immediately bring it to a positive number by use of an anytime card, that player has lost the game and you have won.