Microtransactions

Microtransactions, also called Micropayments, are small transactions found in online games and services where a user pays a one-time fee for access to a piece of exclusive content (virtual goods). This could be pretty much anything—a cute new hat for your Virtual Paper Doll, a cool new piece of armor, a temporary power-up, whatever. It could even just be a shortcut to content you could access for free—for example, you might pay real-world money for a cache of the in-game currency. The Virtual Goods can be bought directly, but it's also common for your real-world money to buy some amount of special in-game currency to spend in a special shop.

 ATT Store= You need more All The Tropes Bucks to see the rest of this trope's definition. Please enter your credit card details to continue. Second Paragraph Pack (US$0.99)= This is the most common form of Bribing Your Way to Victory because it generally allows you to pay as much as you like (although payments are often framed as "donations"), giving the richest players the ability to outpay everyone else. The most extreme cases can require players to pay to access vital game content, resulting in an Allegedly Free Game. However, it's entirely possible to have Micropayments without giving an unfair advantage to those who pay—for example, by making the exclusive content strictly cosmetic. Third Paragraph Pack (US$0.99)= Freemium is a Sister Trope that sometimes overlaps—a Freemium game that also uses Micropayments may offer them as an alternative to, in addition to, and/or as part of a Premium membership. Sometimes games will offer a one-time pack of credits for the Virtual Goods for free to give players a taste of power, in hopes that they'll come back to buy more—this is roughly analogous to a 30-Day Free Trial. Fourth Paragraph Pack (US$0.99)= The difference between this trope and Real Money Trade is that Microtransactions are sanctioned and sold by the game itself, whereas Real Money Trade is done by third parties, without the involvement of and, usually, against the wishes of the game's publisher. 

LARPs

 * NERO, a live-action role-playing game, lets you buy Experience Points for money.

Video Games

 * World of Warcraft players can purchase special mounts from the Blizzard store. They differ from ordinary mounts only in appearance.
 * Dungeons and Dragons Online is an MMORPG which requires paying real cash to unlock certain areas, purchase powerful equipment or unlock certain classes.
 * Second Life's has an in-world currency, "Linden Dollars" (or Lindens, named for the developer Linden Labs), which can be freely converted to and from real world currency. The exchange rate is adjustable, according to a supply-demand index called the "Lindex". Lindens are required to rent parcels of land and to upload textures, sounds, animations, and mesh models which you've created yourself, but mostly Lindens are exchanged among players in order to obtain clothing, hair, vehicles, houses, furnishings...whatever can be created in-world. It's perfectly possible to enjoy Second Life without Lindens, but most players eventually find something to spend money on.
 * Entropia Universe, which also has (extremely tedious) ways of getting the virtual money without paying anything in Real Life.
 * Three Rings Design's games have a separate currency is used for all the things players would normally have to buy a subscription for. Naturally, this currency is bought with real money, but can be traded afterwards.
 * Iron Realms Entertainment games such as Achaea games use "credits", which can be bought with real money. Credits are traded for gold and items in-game at a varying exchange rate, but the credits-to-real-money rate remains constant.
 * Battlefield Heroes has clothing available to all players, but some of it must be bought. Strictly cosmetic, though.
 * Kingdom of Loathing has the Mr. Accessory, which you receive by donating $10 to the game. It is generally valued at about the amount of meat (in-game currency) that a reasonably well-equipped character could expect to make in a month's worth of farming for it. Because it is very easy to sell the accessory at the current market price, the price works as a very practical real-money-to-meat exchange rate, albeit a one-way one (the accessory's price also serves as a key indicator of the in-game economy).
 * Maple Story sells Money Sacks, which is exactly what it says on the tin. The downside? The illegal market for such things has better rates.
 * Dragonica. It allows players to sell most in-game items for cash points instead of the standard currency.
 * Cards in Magic: The Gathering Online are bought from packs in the online store, just like real cards. They can be traded, bought, and sold freely among players, although "tickets" (normally used for tournament entry fees) are used as the de facto currency instead of dollars.
 * The Mann Co. store in Team Fortress 2. The in-game store has just about every item in the game, all of which can also be obtained through the random drop system. There is still a small market in Unusual hats, something of a status symbol amongst players. Three hats in particular, Bill's Hat (from the Left 4 Dead series), Max's Severed Head, (from the Sam & Max series) and the Earbuds, when Team Fortress 2 was released for Apple computers, are used as the de facto currency for anything to expensive to easily be paid in metal.
 * Portal 2's multiplayer mode has its own shop where players can pay real-world money to unlock special emotes, accessories, and so on.
 * War Of Legends has "WoLCash" used to purchase in-game items and bonuses.
 * All of Zynga's games, including FarmVille, Mafia Wars, and many others, work this way.
 * Gaia Online has AutoCash.
 * Bloodline Champions lets you spend real money to unlock characters. However, you can play your way to most of the things in the store, and nothing that can be bought with real money affects gameplay in any way.
 * Pangya has "Cookie" items that you buy with real-world money.
 * Atlantica Online makes its money by means of an Item Mall, where various items can be bought for real cash, such as the Blessing Potion (which makes the players group much stronger for a limited time), Mounts (faster movement and other boni) or certain valuable items that can also be gotten ingame. All these items can also be traded with other players, allowing customers to make ingame money for real money as well, provided they can find someone rich enough. Some items are also occasionally given away for free or can be found during seasonal events.
 * Burnout Paradise has a variety of downloadable content, the majority of which is new vehicles.
 * Cyber Nations lets players get tech levels, infrastructure, land, and in-game cash in exchange for donations, but limits players to one donation per month. It's not essential, but it can lead to a nice boost in tax collections if timed right.
 * In the Xbox 360 version of The Godfather: The Game, players have the option of buying weapons and upgrades off of the Xbox Live Marketplace.
 * Mabinogi, as is typical for a Korean MMORPG, has a good deal of this. Originally starting as an Allegedly Free Game by restricting storyline quests, Empathic Weapons, character rebirth (a vital game mechanic), and certain other content to paid subscribers only; the "Pioneers of Iria" expansion released all content to free players, including empathic weapons and free character rebirth. Despite this, there remain a considerable number of game-enhancing features that are only available in the premium cash shop, or to premium subscribers.
 * To unlock cars early in Need for Speed: Carbon, Pro Street or Undercover, buy them for real money on XBox Live or PSN store.
 * Sven Coop, a mod for Half Life, allows people to "donate" money to its creators for permanent weapon enhancements—namely, their Uzis do double damage, and they can use armor to boost the damage on their melee weapon.
 * Tetris Online Japan. You use TP to increase your stats, which affect how many piece previews you can see, how fast pieces move across the field when you hold left or right, the speed of the line clear animation, and so on. The higher the stat, the faster you can play. Of course, this can give quite an advantage. TP is earned by playing and winning games, at 10-34 TP per game depending on performance. It also takes a total of 9,700 TP to max out each stat of the 5 stats. But for 105 yen each, you can buy a "Point Scratch" that gives a random amount from 500-10,000 TP when used. "Premium" version subscribers paying 315 yen a month get another 300 TP per month.
 * Zhengtu Online, a Chinese MMORPG deliberately designed from the ground up for gold buyers. The game physically blocks you from advancing without buying experience and items for real world money.
 * Combat Arms has a lot of equipment that can only be bought, or more often, rented, with real money.
 * Battle Stations allows the player to buy rare items, which usually require a lot of luck-based exploring or questing to acquire. There are, however, three items for sale which cannot be found via exploration. These items can be traded on the ingame auction, though, so a wealthy character could try and get them there instead. Also in the cash shop are Action Point packages, allowing the player to gain more Ap than the regular Ap regeneration provides.
 * Playfish games like Pet Society and Restaurant City have separate coins (generated in-game) and cash (real money) counters.
 * Disgaea 3: Absence of Justice allows you to purchase and download additional sidequests during the post-game, almost all of which have new characters as rewards.
 * ''BlazBlue:
 * Calamity Trigger lets you pay a small fee to unlock the "Unlimited" forms of some characters, instead of playing for them.
 * BlazBlue: Continuum Shift went the extra mile by making it much harder to unlock "Unlimited" characters without paying for them. You can also unlock Mu-12 by either spending several hours playing story mode, or just buying her as well.
 * League of Legends uses Micropayments as a shortcut for unlocking heroes. Micropayments are also the only way to buy character skins, which are entirely cosmetic.
 * Lord Of Ultima. Free to play, but one can purchase "diamonds" that in turn allow for the purchase of artifacts that give resources, build-time increases, etc. The game limits how frequently you can use them, though.
 * S4 League. Those who are willing to shell out real money get slightly more effective weapons, flashier clothes, and will gain levels faster. They also don't have to worry about buying their weapons with in-game currency, which is fairly difficult to acquire. However, the advantage supplied by the paid-for weapons is fairly minimal, and none of them are unique; they're just optionally reskinned versions of the stuff everyone gets. Likewise, the paid-for clothes just look good, they don't offer any concrete tactical advantages.
 * All Artix Entertainment games (Adventure Quest, Dragon Fable, Mechquest, Warp Force, Epic Duel, and Adventure Quest Worlds) have the basic storyline and most equipment available for free, but the best weapons, armor, Titan quests and battles (best for farming!), and so on are only available to upgraded players and (in the case of equipment) often only for special currency that must be purchased with real-world money. (although small amounts can be gotten rarely in AQ, DF, and MQ) The worst for it is probably AQ; MQ is probably the best, but DF and AQW both have an awful lot of content available for free players.
 * Echo Bazaar allows you to buy Fate with real money. Fate is obtainable in game on very rare occasions, and can be used for mundane functions like restoring your opportunities deck to unlocking new and complex story inlets.
 * Tales of Vesperia has this. Some of the stuff is rather easy to get later on in the game, and some of it is free too, so the advantage is mitigated somewhat.
 * Project Blackout sells special, more powerful equipment for real money.
 * World of Tanks, an MMO tank-simulation game, operates on microtransaction, also mixing in a Freemium system. You can purchase gold, which can be either spent on a "premium account" that gives you a boost in experience and credit generation, or various in-game items and tanks.
 * Rock Band has 300 or so songs found across the five released games, and a handful available on "track pack" discs. The other 2500 or so require individual purchase at $2 a pop, or in packs which cost a little less.
 * Civilization V has DLC for civs, wonders, and map styles.
 * RuneScape MMORPG now allows the purchase of extra "spins" on something called the "Squeal of Fortune", a Wheel of Fortune parody on which you can win assorted (mostly junk, but some very good) prizes, as well as experience rewards.
 * Failed spectacularly in EVE Online, when the release of $70, purely cosmetic monocles caused in-game riots.
 * To unlock all the characters and power-ups in Temple Run, you need coins. These coins can be gathered within the game, but for the impatient they are also available for real money.
 * Voltage Inc's reverse harem games Pirates In Love and My Forged Wedding run on microtransactions. The player downloads the free app, and then can buy as many or as few routes as desired.
 * Parodied in DLC Quest where everything has to be bought from the ability to move to the left to the ending of the game. Fortunately, you have to pay with in-game money.

Web Original

 * Extra Credits Discussed the topic in detail in one of its videos, calling it a useful tool that many games should embrace and offering some do's and don't's to any developers interested in adopting the model. (Build the content with the payment model in mind, give free players a way to earn paid currency without paying, avoid Bribing Your Way to Victory, etc.)
 * Many game apps on Facebook use Facebook coins, which are bought with money. Some use the direct method as well.