Booze-Based Buff

In Real Life people drink alcohol. One could fill several essays with discussion of the biochemical and sociological reasons for this, but the main reason is simple: Because it's fun.

We run into a problem when we try to depict this in Video Games, however. Namely, a realistic depiction of intoxication would have the player character stumbling around with reduced motor skills for a while, and possibly waking up the next day with a splitting headache. Or in other words, not fun.

So what are game designers to do if they want to include booze in their games, but still want the players to actually use it? Simple. Make it a power up!

While it may not be entirely realistic to have alcohol increase one's fighting ability, the only other options are to not include it at all, or to relegate it to the status of Vendor Trash or Poison Mushroom.

When drunkenness is included, it is usually exaggerated and short-lived, sometimes with vision blurring of Mushroom Samba proportions lasting for only a few seconds.

Someone in fiction who gains such powers is a Drunken Master

Action Adventure Games

 * Done in Okami and its sequel Okamiden. Even the great god Amaterasu likes to quaff some Steel Fist sake before laying the celestial smack down. It's also inverted in the boss fight with Orochi, who is completely invulnerable... until you use hydrokinesis to force-feed him the best sake in the entire world, thus getting him so drunk that he becomes vulnerable to your attacks.
 * In Overlord Minions and Dwarves fight better when drunk.
 * In the Wild West Wide Open Sandbox game GUN, the player character heals by drinking out of the flask of whiskey he keeps with him. Justified in that it's not actually healing you, it's just dulling the pain so that you can keep fighting.
 * Inverted in Leisure Suit Larry: Magna Cum Laude: drinking makes the protagonist clumsier, increases his need to urinate and makes him more likely to say something inappropriate in conversation. Truth in Television, anyone?
 * In Catherine, the more Vincent drinks at the bar, the faster he moves in the Nightmare stages.
 * Bastion treats alcohol as equipment rather than consumable items, meaning the bonuses he gets from them are permanent until you change them. The higher the protagonist's level, the more kinds of alcohol he can equip at once.

First-Person Shooter

 * In System Shock 2 and Bioshock, you can drink any booze you find lying around to restore your Health. This comes at a penalty to your PSI/EVE, however. You get the opposite effect from tobacco.
 * As absurd as it is that drinking and smoking cancel each other out, it's worse, because they give you more than they take away, meaning that doing both in equal amounts is good for you.
 * Drinking booze too fast does mess up your aim and vision, just not for very long.
 * And then in Bioshock then you can equip the Booze Hound tonic that turns alcohol into a pure power-up, aside from the minor vision and aiming penalties.
 * Possibly first used in the old Redneck Rampage PC game, where booze restored health but also blurred vision and seriously slowed and eventually caused an Interface Screw with aiming and walking controls.
 * In Condemned 2: Bloodshot, if the player doesn't make Ethan regularly consume alcohol, his vision blurs and his aim becomes unsteady.
 * Justified as Ethan is suffering from alcohol withdrawal. Like any drug, drinking alcohol on a regular basis causes your brain to become dependent on it.
 * Deus Ex: In the unmodded game, any alcohol drink would give you two points of health, at the cost of blurred vision for roughly about a minute or so. Justified as the player character's nanites would instanly metabolize any product consumed.
 * Deus Ex Invisible War: Averted, alcohol now takes away health.
 * Deus Ex Human Revolution: Alcohol will blur your vision again and give you health, like in the original game, but this time, your health will be pushed beyond the normal limit, giving you extra health. This health won't be recovered through the game's regenerating health though.
 * In STALKER, vodka cures radiation poisoning.
 * Which causes problems while adjusting to Fallout 3; reaching for the vodka instead of the Rad-Away is rather embarrassing.
 * Truth in Television as some studies show.
 * Drinking alcohol in Bulletstorm will cause your character's aim to go awry, and his vision to blur, but to counterbalance it, every kill you score while intoxicated will net you a score bonus. Drinking 20 bottles (that must be found throughout the game) gives you an achievement/trophy.
 * On the other hand, inversely, just shooting the bottle gives you some immediate points without having to mess your vision up, and shooting 20 also gives you an achievement/trpohy.
 * Drinking beer in Duke Nukem Forever slightly blurs your vision, but Duke takes less damage from enemy attacks.

Hack and Slash

 * In Dynasty Warriors, Samurai Warriors, and Warriors Orochi, giant clay pots (as in, large enough for a grown man to take a bath in) of alcohol fill your Limit Break meter.
 * Similarly, sake gourds in Sengoku Basara fills your Basara Gauge. At least two characters, Maeda Keiji and Shimazu Yoshihiro, have attacks that explicitly involves imbibing alcohol.

MMORPGs

 * In World of Warcraft, alcohol will blur your vision, make your character walk crooked, and make you misjudge enemies' levels if you drink enough of it, but some of it increases your stats temporarily. The chat box displays your intoxication level as feeling tipsy, drunk, etc (along with an Alcohol Hic or two). When you get to "completely smashed" you start to have hallucinations and your characters performs a drunken vomit.
 * It also causes you to "slur" some words by randomly adding an 'h' after some 's'es, leading to one early patch note reassuring people that they would no longer accidentally talk about excrement while try to sit.
 * Inverted in Warcraft 3 (and Defense of the Ancients), where the Pandaren Brewmaster can cause a negative buff on enemies by using the Drunken Haze ability. It also helps if he should decide to set the enemy on fire.
 * In one Wildhammer Dwarf daily quest in the Twilight Highlands in Cataclysm, using the kegs of beer gives you a significant and stacking bonus to your attack.
 * Stat-enhancing alcohol is in the game, but most of it is only available during the Brewfest world event.
 * In Guild Wars, there are three Player Versus Environment-only Eye of the North skills that can benefited while you are drunk. Of course, the sucky part of this is that your screen is blurry while you are drunk, but that can be turned off with your interface options.
 * In Kingdom of Loathing, booze is one of the main ways of gaining more adventures per day.
 * Note that if you drink too much, you enter drunken stupor: a set of adventures, all producing negative (abet minor) effects. So drink in moderation, or binge and wait until tomorrow.
 * There also exist several drinks which, in addition to providing adventures, also provide actual buffs. Also, absinthe, which strangely doesn't get you drunker, instead temporarily opening a new set of zones to adventure in.
 * Sneaky Pete's day. Drink in moderation, it's the same as normal. Go into a stupor, still the same. Get completely blasted, you get a new area.
 * In Lusternia, drinking can dull damage. Certain races (particularly dwarves - natch) can handle their beer way better than others. And Brewmeisters (a trade) can handle it better still, in addition to brewing their own magical draughts. Consequently, a drunken dwarf Brewmeister is a force to be feared.
 * In Urban Dead, cans of beer and bottles of wine both increase your health by one, but because drinking either one takes a whole turn, it's usually better to just search for a medkit.
 * In Nodiatis, the "Alcoholic" class gets increasing protection from Standard Status Ailments by being "buzzed".
 * In Runescape a variety of ales can be brewed via the Cooking skill. These provide temporary boosts to specific skills when drunk.
 * However, alcohol of all types reduces your chance to hit in close combat.
 * In some MUDs, being drunk boosts your healing rate. At least one had a sword that made you drunk when you used it.
 * In The Lord of the Rings Online, consuming too much beer or wine will progressively blur your vision, depending on how much, until eventually you're basically seeing quintuple.

Platform Games

 * In the Amiga game Flood, a cocktails will fully restore your health and oxygen, and a pint of Guinness is an extra life.

Real-Time Strategy Games

 * Gragas, a champion in League of Legends, is based entirely around being a fat guy who brews and drinks magical wines and ales. Every time he uses an ability, he takes a drink to restore a portion of his maximum health, and he can guzzle down a whole cask of brew to gain back mana, temporarily increase his attack damage, decrease all damage taken temporarily, and as part of his passive, casting that ability will cause him to heal a small percentage of his total health pool over a few seconds.

Role-Playing Games

 * Project Zomboid: Alcohol can serve as a poor man's substitute for drugs, at the cost of lost coordination and energy.
 * In the earlier The Elder Scrolls games, you could throw back drinks to gain minor, temporary buffs... but not only did you get blurry vision, if you drank enough, it could kill you on the spot from alcohol poisoning!
 * In the later games (Morrowind and Oblivion) cheap drinks will generally buff one attribute will draining another, or restore your stamina. It is possible, however, to negate such attribute drains by casting a recovery spell. Expensive, quality liquors like Flin or Cyrodilic Brandy didn't have any adverse effects.
 * Since different drinks diminished different stats, it was possible to drink two or three, and have the penalty end up on a non-combat stat, such as Personality.
 * An extreme example is the drink Sujamma from Morrowind. It massively boosts strength while dropping intelligence. And the effects stack. Great when one needs titanic strength for a minute.
 * Alcohol in Fallout 3 gives you a small boost to Strength and Charisma, at the expense of intellect and with a chance of addiction.
 * All the previous games' alcohol did was reduce perception by 1, for a very short time. Additionally, you could use it on other targets besides yourself. This led to the interesting development of a player walking up to the last boss in 2 with a 12-pack of beer...
 * Fallout 2 took this to another level. In addition to booze, there were 4-5 street drugs which would give you stat bonuses, at the cost of minuses to other stats and a chance of addiction. A Good Bad Bug allowed you to gain unimaginable agility by constantly using Jet until you were addicted, then drinking a little alcohol (which canceled the addicted status and made the agility gain permanent).
 * In Fallout: New Vegas, one of your Companions, Cass, gives you the 'Whiskey Rose' perk. This lets you drink Whiskey (Boosts your STR and CHR at the cost of INT and PER) without any adverse effects, making her the preferred partner of many Unarmed and Melee based characters.
 * You can also make your own wasteland alcohol, one type has a possible intelligence penalty of -6. If you have average intelligence (5) this can take you into Improbably Low IQ territory.
 * In Odin Sphere, Lord Brigan gains buffs from drinking his own alcohol, but when he pours it onto the PC's face, it makes him/her dizzy.
 * Atelier Judie has enemy bears that will feed you wine, which makes your accuracy drop dramatically.
 * In Baten Kaitos Japanese Rice Wine actually revives the player, and beer/red wine/sweet wine can heal. Even a certain miniboss will use "Rough 'em up drink," which increases defense.
 * In Orcs And Elves for cell phones and the DS, you can drink ale to increase your stats but decrease accuracy. Additionally, the screen slowly sways back and forth the more drunk you are.
 * During the Wild West chapter of Live a Live, booze and smokes are your primary healing items. They all drop your stats when used, however.
 * In The Witcher videogame, drinking makes the screen wobble and blur, makes Geralt stagger around and reduces fighting ability, but several talents can be taken that only activate when intoxicated. In addition, strong, quality alcohol is used as a base for most potions.
 * In Final Fantasy XI, most fruit-based drinks cause MP to regenerate (adding milk to it makes it regenerate HP). The one made from decayed grapes is the strongest. In two senses of the word.
 * The PS2 and XBox release of The Bards Tale give the player the option of temporarily increasing (or, in some cases, decreasing) some of the eponymous Bard's stats by buying a drink from any of the several taverns he comes across in his quest. The barkeeps even go to the trouble of describing the taste and quality of the selected brew when you take a look at them.
 * Used by Zegram in Rogue Galaxy -- "Drunken Burst," in which a swig of grog increases the attack power of all allies.
 * Jade Empire has Drunken Master style, only usable if Henpecked Hou is in your party. Booze is used to boost your health, but slows your reflexes. This is used to hilarious effect in one of the final battles where you team Hou up with Ax Crazy Black Whirlwind, who is over the moon with delight over being able to drink and fight (his two favorite things in the world) at the same time!
 * Being drunk is how the magic works in Dubloon.
 * In "Phantasy Star Universe" and related games the Photon Art "Ikk Hikk" involves drinking alcohol, beating up your opponent, breathing fire, passing out, and then flailing your arms and legs.

Shoot Em Ups

 * The modern NARC game does this with drugs. Crack makes you a crack shot, for instance.

Simulation Games

 * In Dwarf Fortress all dwarves -- even babies -- are alcoholics, and going a significant amount of time without alcohol will cause efficiency and happiness to plummet.
 * In The Sims Medieval, Sims get a positive buff from drinking, and an extra one if the drink actually tastes good. Those with the "Drunkard" Flaw get a negative buff from not drinking, but don't get any more positive effects from drinking than those without the flaw.
 * In Frontier Ville, you can get drinks from the Saloon such as Loyal Pioneer, which lets you do 10 actions at a neighbour's homestead instead of 5 and Quick Draw Quaff which lets you do 5 actions using only 1 energy.

Survival Horror

 * Edward Carnby from the Alone in The Dark series drinks from various hip flasks scattered about to gain health.
 * In Eternal Darkness, Edward carries a flask of "liquid courage"; drinking it restores sanity. There must be something to it, since Edward is one of the few characters who doesn't wind up dead or insane after his adventure. (Well, not immediately after, but that's beside the point.)
 * Dead Rising: Both Frank and the gun store owner drink wine by the bottle to replenish health.
 * In the sequel, Chuck downs an entire bottle of Whiskey (the same you can make a molotov with, holy crap!) in a few seconds. Although the risk of getting sick to your stomach arises when consuming more than one alcoholic item shortly after another (which results in vomiting uncontrollably).
 * Done again by Frank in Marvel vs. Capcom 3. He can take a swig of alcohol, allowing him to take more pictures and grow levels quicker. However, after a while he'll hunch over and groan in pain allowing the other player to attack.
 * Bottles of hard liquor such as Hot Sake or Tequila serve as healing items in Shadows of the Damned. It's justified by the fact that in the Underworld alcohol heals you rather than destroys your liver.
 * Dead Island has the Alcohol item. It's useless when drunk, only giving you a severe case of Interface Screw, unless you're playing as Logan, who, once you get the appropriate skills, can get increased strength and/or regenerating health when drunk.
 * Die 2 Nite currently has 3 alcohol based items that restore a players AP, but gives them a hangover the next day. Of course, this is justified as it is specifically mentioned that the items are really potent. (One is 85% proof!)

Tabletop Games

 * Dungeons and Dragons' Drunken Master Prestige Class can drink alcohol to provide bonuses to Strength or Constitution at a penalty to Wisdom and Intelligence. At higher levels Drunken Masters can heal themselves by hitting the booze, or set the alcohol inside them on fire and spray it as a Breath Weapon.
 * In the Baldur's Gate series, over imbibing would only cause the character to become drunk at penalties to attack and armor. A moderate consumption would give you a slight morale boost. Still mot worth it, though.
 * GURPS addresses this. The Drunk and Tipsy conditions temporarily reduce DX and IQ but make it easier to resist the Cowardice and Shyness disadvantages.
 * From Martial Arts the Drunken Fighting perk plays this straight.
 * The drunkenness rules were originally written for the Sourcebook of Callahan's Crosstime Saloon.
 * The Dungeon Fantasy supplement Taverns gives details on several special drinks that can give you minor benefits.
 * In Exalted, there is a Martial Arts school which teaches the Orgiastic Fugitive Style which increases your ability in the art in line with how debilitatingly inebriated your character is. This, by the way is a Celestial level martial art meaning that its inventor was either a God or one of the 700 Celestial Exalted.
 * Feng Shui has the fu path of the Empty Bottle, which caters to Drunken Master types such as those played by Jackie Chan.
 * Unknown Armies has Dipsomancy as one of its magical paths. Followers must be inebriated in order to gain magical charges, and sobering up removes all of their current power.
 * The boardgame Red November (where you play an all-gnome crew on a VERY disaster-prone submarine) has the Grog item, which provides a + 3 bonus to any one task, and allows you to enter burning rooms even if you don't have an extinguisher. However, every time you do that, you have an increasing risk of passing out for ten minutes. As the game takes place over less than sixty minutes, this could be very dangerous. Even moreso if the room you're in springs a leak, or catches on fire...
 * Hong Kong Action Theatre has Joi Kuen (Drunken Boxing) as a "substyle" of kung fu which can be added to any style, which adds Dodge and Nerve Strike as additional maneuvers to any existing style. In addition, there's the "Drunk" Signature Move from the To Live and Die in HK supplement which allows a character with the signature to ignore all damage penalties for three combat turns if he or she can take a good swig during a fight, as well as adding a + 1 bonus to Dodges and Nerve Strikes due to their Joi Kuen.
 * In the card game Bang!, taking a drink (by playing a Beer card) heals damage.
 * Drunkenness in a typical New World of Darkness game confides a small bonus to all Social actions, but a corresponding penalty to Initiative, Wits, and Defense.
 * In Hell MOO alcohol will reduce your reflexes, make you vomit, cause you to slurr your speech and pass out, but will also increase brawn and with the correct mutations heal wounds.

Third-Person Shooter

 * In Wet, a grindhouse flick-inspired game, taking a swig from a bottle of whiskey fully restores Rubi's health.

Turn-Based Strategy

 * Used in Rezerwowe Psy, a somewhat kid-unfriendly and controversial Polish squad-based tactics game.

Non-Video Game Examples

 * Legend Of The Drunken Master portrayed Jackie Chan being a better fighter while drunk (with the reasoning of increased pain tolerance and improved flexibility. Also, real life Drunken Boxing is pure Confusion Fu: Jackie Chan's movie and video game series regarding being a Drunken Master thus assumes it's easier to execute it when actually drunk). He quits booze at one point in the plot, but in the final fight, he recovers from a hopeless fight by drinking pure grain alcohol.
 * For a possible real life example, look at Buckfast Tonic Wine. At 30 proof and containing more caffeine per volume than Red Bull, its considered by many to be the source of a great deal of Scotland's violent drinking woes, due to the obvious problems that come with drunken, violent disaffected youth hopped up on enough caffeine to kill a horse with a glass bottle literally on hand. True or not, it has earned some rather entertaining nicknames, such as "Commotion Lotion" and "Wreck the Hoose Juice."
 * Many long-term alcoholics work better after a smaller glass of booze -- their body has become accustomed to alcohol and the lack of it brings very unpleasant things, even before true delirium tremens appears: shaking hands, fatigue, stumbling etc.