Gameplay
A deck typically consists of any combination of four heroes and/or villains, three in the frontline and one in reserve. The rest of the deck consists of fifty-one cards representing offensive and defensive actions that can be taken by the characters or their allies. Each player also chooses a set of 7 mission cards, that represent their team's goals. Finally, each player may also have a homebase and/or a battlesite that represent where their team is from and where the battle will take place. The goal of the game is to either KO the opponent's entire team, or to complete all 7 mission cards (or defeat all 7 of the opponent's).
Players take turns playing attacks back and forth. During a battle, characters may become hurt, and if they are hurt enough, they may be KO'd and eliminated. In addition, each team ventures a number of mission cards, and the winner of the battle completes those missions, while the loser's missions are defeated. If neither team concedes, the team that did more damage to the other is the winner.
Characters
Each character card has a picture of the character or characters it represents, the name, and three or four numbers representing their power grid. In the initial game and its first few expansions, the only power grids were Energy, Fighting, and Strength, but in the DC Overpower Expansion Set, Intellect was introduced as the fourth type; it was needed for some of the DC characters, like Lex Luthor, whose main advantage was not their fighting or strength, or their powerful weaponry, but rather their ability to outwit their opponents. DC Overpower also introduced hero/villain codes; most characters and specials were labeled either as villains or heroes, and mixing the two was restricted in a DC-only game (no restriction in Marvel, Image or mixed games though). Characters are normally used only to represent the team a player is using, but they are also used as activators. A player's team consists of four characters: three on the front line, and one in reserve, who moves up to the front only when one of the other characters is KO'd.
Power cards
Power cards each consist of a number from 1 to 8 and a type, Energy, Fighting, Strength, Intellect, Multi-Power, or Any-Power. Power cards can be used as an attack of the level of the number, or as a defense of the level of the number. A character can play a power card whenever their grid is high enough. For instance, a character with 6 energy could play any energy power card from 1-6, but couldn't play 7s or 8s. (This requirement is the same on attack or defense.) Multipower power cards can be used in any of the types shown (either all four, or just Energy, Fighting, or Strength); their type may be chosen as they are played.
Special cards
Special cards each show the name of a particular character, and have a name and a description. Special cards can only be used by the character named on it. Specials serve a variety of purposes; some are attacks only, others can be used for defense only, while others affect the game in other ways, for instance healing hits that heroes have taken, or affecting missions directly, or interfering with the opponent's ability to play attacks. Some special cards are 'any hero' or 'any character' specials, and can be used by any character. Each character has their own unique set of specials. Some characters' specials are very straightforward attack or defense, while others have much more unusual abilities; this is how the unique character of the various superheroes and supervillains is shown in the game.
Universe cards
Universe cards come in a few categories, but generally are usable by any character that meets the usage requirement. For example, one type of universe card (basic universe cards) provide bonuses to power cards: such a universe card might be usable by any hero with a 7 or higher in strength, and provide a +2 bonus to a strength power card played with it. The most popular type of universe cards are teamwork cards, which themselves count as a level 6 attack, and give a bonus to a follow-up attack made by a teammate in a different power type than the original attack; this is popular because a level 6 attack is a relatively powerful attack, and the ability to make multiple attacks in a row is beneficial.
Tactic cards
These cards are seen much more rarely. Some tactic cards are doubleshot cards which lets two characters work together for a combined attack. The others are artifact cards, which either permanently or temporarily provide a benefit to one of the team members, such as enhancing their power grid.
Event cards
Event cards are not used in battle. Rather, event cards are played before a battle and then replaced; events can affect the coming battle or the state of the game in many ways, for instance, returning a KO'd character to play, disallowing the use of specials for the battle, etc. Each set of 7 mission cards comes with its own set of events.
Location cards
Locations have a name and describe a set of conditions for a team; usually, a list of six characters that can be used. In addition, they have an 'inherent ability' -- something that modifies the way the game is played. Locations can be used in two ways: either as a homebase or as a battlesite. When used as a homebase, one's team must match the team description, and the inherent ability applies to the game. Battlesites are somewhat different; they are an alternative to the ability to use 'any hero/character' specials. Instead of those specials, the deck may include character cards, called activators that appear on the list in the battlesite, and the battlesite itself may store specials those characters can play. A character card played as an activator is exchanged for one of that character's specials in the battlesite, which is then used like an 'any hero' special.
Attack, defense, and damage
Generally, the two players take turns attacking until one gives up or until both players are out of cards for the turn. Most attacks are numerical attacks, such as a power card attack against a character. Once an attack is made, the target has the opportunity to defend. A numerical defense can be played if the number played in defense is at least as big as the attack level (so a power card can be defended by any power card of equal or higher value, but type is unimportant). Cards other than power cards can also be used in defense; some universe cards can be used to provide a bonus to another defensive card, and specials can often defend against an attack. In some cases, specials that set up a lasting effect (for example "Hulk cannot attack or be attacked for remainder of battle") can be played as a defense. If a numerical attack isn't defended, it becomes a hit and immediately counts as damage.
Most numerical attacks are energy, fighting, strength, or intellect attacks, but some are multiple types, and some have no type. Characters are KO'd in one of two ways. Cumulative KO occurs when a character has taken 20 total damage, regardless of how many attacks or what types they are. Spectrum KO occurs when a character has taken damage in three of the four different power types: multi-type hits can be changed retroactively in order to make spectrum KO occur.
Some attacks are non-numerical (for instance, specials that say "Target opponent cannot attack for remainder of battle"). Such attacks can generally only be defended by specials; if they are not defended they do no damage, but instead the described effect takes place. If they are defended, nothing happens.
If a player doesn't wish to make an attack, they have the option of conceding the battle instead. If they don't concede, their opponent will get a chance to attack them next.
Battle phases
Each battle consists of several phases: first, each player draws 8 cards. Then, each player discards duplicate cards until they have only one of each type. (What is considered the same for duplicate purposes varies among the card types. For instance, two power cards are considered duplicates if they have the same number, even without the same type, whereas two special cards are only duplicates if they are exactly the same special). Players also discard unusable cards. Next, players take turns 'placing' cards. Cards, generally, can be placed on a character that can use them. Placed cards can only be played by the character they are placed on. The advantage to this is that placed cards that are unused at the end of a battle remain where they are, whereas unused cards in a player's hand are discarded. Each character may have one of each of the four types of cards placed on it: power cards, specials, universe cards, or tactic cards. After placing, the players decide on their venture—how many missions they are willing to risk on the battle. Then, the battle itself takes place. After the winner is determined, the next battle begins.
Strategy elements
Some of the interesting aspects of strategy in Overpower are the following. First of all, specials are often more powerful than other cards but they have the disadvantage that only one character can use them. It is critical not to make a deck too overloaded with one character's specials unless that character can be defended very well; otherwise, the deck would be badly crippled once that character is KO'd. Teams typically share certain power grid similarities, especially high ones. For instance, a team may consist of various characters with 7 or higher Energy ratings. This way, high-level power cards can be energy and usable by all characters.
Another key tactic in OverPower is the idea of placing and conceding: the idea is to take some time to heavily arm your team. Your opponent may gain a mission or two but you may get a significant advantage in the battles that follow. However, placing also reveals more information to your opponent about the cards you have available to use for the round.
Many characters have specials that allow them to avoid an attack; this creates an interesting incentive to attack other characters. Similarly, some characters have specials that allow a teammate to avoid an attack. This also creates great opportunities for bluffing; you may play a dangerous character that has an avoid special, but not actually play any, yet act like you might have one. Indeed, having a good poker face, and bluffing often, are very useful skills in Overpower.
