Power-up

In video games, a power-up is an object that adds temporary benefits or extra abilities to the player character as a game mechanic. This is in contrast to an item, which may or may not have a permanent benefit that can be used at any time chosen by the player. Although often collected directly through touch, power-ups can sometimes only be gained by collecting several related items, such as the floating letters of the word 'EXTEND' in "Bubble Bobble". Well known examples of power-ups that have entered popular culture include the power pellets from "Pac-Man" (regarded as the first power-up) and the Super Mushroom from "Super Mario Bros.", which ranked first in UGO Networks' "Top 11 Video Game Powerups".
Items that confer power-ups are usually pre-placed in the game world, spawned randomly, dropped by beaten enemies or picked up from opened or smashed containers. They can be differentiated from items in other games, such as role-playing video games, by the fact that they take effect immediately, feature designs that do not necessarily fit into the game world (often used letters or symbols emblazoned on a design), and are found in specific genres of games. Power-ups are mostly found in action-oriented games such as maze games, run and guns, shoot 'em ups, first-person shooters, and platform games.
History and influence.
Origins of the term.
"Power-up" and "1-up" are examples of a common form of "wasei-eigo" (Japanese pseudo-Anglicisms), in which the word "up" is prefixed by some desirable quality. The general meaning of "X-up" in Japanese is "this will increase your X", and this construction is regularly used in areas such as advertising. This is similar to another phrase, "X get!", as seen in Super Mario Sunshine's Japanese version's "Shine Get!" phrase.
First instances.
"Pac-Man" from 1980 is credited as the first video game to feature a power-up mechanic. Every maze in the game contains four Power Pellets which temporarily give Pac-Man the ability to eat ghosts, turning the tables on his pursuers. The effect of the power-up was illustrated by one of the first cut scenes to appear in a video game, in the form of brief comical interludes about Pac-Man and Blinky chasing each other around. The power pellet entered popular culture with a joke on video game controversies regarding the influence of video games on children.
In 1984, "Sabre Wulf" introduced power ups in the form of flowers which, when blossoming, provided effects such as speed up and invincibility.
In 1985 "Super Mario Bros." introduced the Super Mushroom, which has entered popular culture, being described as "the power-up". The original game idea was to have an always big Mario as a technical advance, but later the power-up was introduced to make him "super" as a bonus effect. The development team thought it would be interesting to have Mario grow and shrink by eating a magic mushroom, just like in Alice's Adventures in Wonderland. Other power-ups introduced in this game were the Super Stars and Fire Flowers, which gave Mario invincibility and the ability to shoot fireballs at enemies, respectively. 
Konami's 1985 game "Gradius" had the first use of a selection bar where the player could select which power-up effect to trigger, instead of having a fixed instant effect.
In 1986 and the years after, the concept of permanent power-ups appeared in the action role-playing genre in the form of "perks".
Types of power-ups.
Power-ups can be classified according to the type of benefit they give the player.
Offensive abilities.
Gives a new weapon, or transforms the player character into a more aggressive form that increases its attack power or makes some enemies vulnerable. This also includes "nukes", which are weapons that destroy every enemy on the screen at once; these are prevalent in many different genres including vehicular combat, run and guns, and platform games. The effect of the power-up can be time-limited, have a limited number of uses, last until the player is hit, last until the player is killed, or last until game over.
Examples:
Defensive abilities.
These typically consist of items like "shields" (usually a "force field") surrounding the character that deflects projectiles or absorbs a certain amount of damage, or invincibility/invulnerability. In the case of invincibility, this is nearly always granted as a temporary bonus; otherwise it would negate the challenge of the game.
Invincibility (or "invulnerability") comes in two main forms: either the player character merely becomes intangible to harmful things, or can also damage enemies by contact. In either case the character is often still vulnerable to some threats, such as bottomless pits. In many games, invulnerability is also temporarily granted after the player gets hit or loses a life, so that the character will not be hurt/killed twice in quick succession. The effect is commonly indicated by making the player character flash or blink or by musical cues.
Examples:
Evasive abilities.
Items which help the player avoid or escape enemies or enemy weapons. This category includes "speed boosts" and other power-ups which affect time, which can be temporary, permanent, or cumulative, and "invisibility" power-ups which help the player avoid enemies.
Access abilities.
Items which help the player enter new or previously inaccessible areas, or "warp" to another level. Access abilities, depending on the game, can be required to progress normally or be entirely optional.
Examples:
Health and life reserves.
Typically consists of items which restore lost health (most typically in med. kits, food, or as energy), items which increase health capacity and 1-ups (which give an extra chance to continue playing after losing, commonly called a 'life').
Examples:
Ammunition and power reserves.
In some games, using certain items or abilities requires the expenditure of a resource such as ammunition, fuel or magic points. Some games use a single resource, such as magic points, while others use multiple resources, such as several types of ammunition. Some games also have power ups which increase the player's maximum ammunition or power capacity.
Examples:
Token abilities.
Items whose main feature is that they are found in large numbers, to encourage the player to reach certain spots in the game world. They have various cumulative effects, often granting the hero an extra life.
Examples:
Trick power-ups.
These power-ups try to trick the player into grabbing them, only to result usually into damage, removed abilities, or player death.
Examples:
Attaining power-ups.
There are many different methods of obtaining power-ups:
Treasure chests.
In many video games, especially role-playing video games, treasure chests contain various items, currency, and sometimes monsters. For certain role playing games, some chests are actually mimics, in which a monster looks like a chest, but will attack the player when they attempt to open it. This is notably seen in the "Seiken Densetsu" and "Dragon Quest" series.
Treasure chests provide a means for the player to obtain items without paying for them in stores. In some cases, these chests contain items that cannot be purchased at stores. Chests may be locked, requiring a key of some sort. For certain games, keys can only be used once, and the key is destroyed during its use. For other games, having a particular type of key means that the player can open any of the chests with a matching lock.
For most games, once a chest has been opened, the contents remain empty, although they may be repopulated with possibly different items during different stages of the game. This is different from perishable containers, such as crates and jars, which tend to reappear if the player exits the area and then returns.
Selection bar.
Instead of having players collect a power-up that is instantly activated, the players may be allowed to select which power-ups they want to use. This is commonly implemented through a 'selection bar' which contains a number of power-up effects. To access the bar, the player must collect power-up items; the more they collect, the further along the bar they can access. The more powerful power-ups are traditionally placed further along the bar, so that more effort is required to obtain them. The selection bar was first used in Konami's 1985 game, "Gradius".
Perks.
"Perks" are a variation of the power-up mechanic, but permanent rather than temporary. The concept of permanent power-ups dates back to the early NES action RPGs, "Deadly Towers" (1986) and "Rygar" (1987), which blurred the line between the power-ups used in action-adventures and the experience points used in console RPGs. An early video game that used perks, and named it as such, was the 1997 computer RPG game "Fallout". Perks have been used in various other video games in recent times, including first-person shooters such as "", "Modern Warfare 2", and "Killing Floor", as well as action games like "Metal Gear Online".