Gamertag

A Gamertag is the universal name for a player's username on Microsoft's Xbox Live. A Gamertag used online must be unique and can be up to 15 characters in length, including numbers, letters, and spaces. Gamertags can be changed using a premium service on the Xbox 360 console (for a price of 800 Microsoft Points), although a given console has a total of four slots for such accounts.

A player's Gamertag account status can be checked using a variety of online tools, which is useful especially when looking for a new gamertag, or confirming that a Gamertag exists. Using a valid Gamertag, any player can be located and messaged from within Live. There are also several websites which allow users of Gamertags to upload photos and information about themselves.

Gamertags can be used in a variety of places, including the original Xbox, the Xbox 360, Games for Windows - Live, Zune, and XNA Creators Club.

Gamertags also contain avatar images (or "gamer pictures"), often associated with certain games or game characters. Individual gamerpics cost between 15 and 20 Microsoft Points, but they are usually bundled into packs; packs of four or five gamerpics usually cost 80 Microsoft Points, while packs of ten typically cost 150.

Gamerscore

The Gamerscore (G) is a measure that corresponds to the number of Achievement points accumulated by a user with an Xbox Live profile. These Achievement points are awarded for the completion of game-specific challenges, such as beating a level or amassing a specified number of wins against other players in Xbox Live matches. Initially, retail Xbox 360 games offered up to 1,000G spread over a variable number of Achievements, while each Xbox Live Arcade title contained 12 achievements totaling 200G. Maximum gamerscore totals per game have been raised to from 1000G to 1750G.

On February 1, 2007, Microsoft announced on their Gamerscore Blog some new policies that developers must follow related to Gamerscore and Achievements in future releases.^[14] All regular disc-based games must have 1,000 Gamerscore points in the base game - the title can ship with fewer than 1,000 points, but anything added later must be free. Game developers also now have the option of adding up to 250 points via downloadable content every quarter after the first year of release. (for a total of 1,750 points) Xbox Live Arcade titles must have 200 Gamerscore and may add up to 50 points via downloadable content (for a total of 250 points).

On May 26, 2007, Halo 2 was the first Games for Windows game to feature Achievements, which counted towards a player's Gamerscore.

On March 25, 2008, Microsoft cracked down on "Gamerscore cheaters" (those who used external tools to artificially inflate their Gamerscore), and reduced their Gamerscores to zero without the option to recover the scores that had been "earned", and branded the player by denoting on their Gamertag that they were a "Cheater".

Gamercard

The Gamercard is an information panel used to summarize one's user profile on Microsoft's Xbox Live. The pieces of information on a Gamercard include:

• Gamertag (in front a silver or gold bar)
• Gamer picture (avatar)
• Reputation
• Gamerscore
• Gamer Zone
• Recent games played

A player's Gamercard can be viewed via the Xbox 360 Dashboard, or online through Xbox.com. The top bar that displays the Gamertag is shown in front of either a silver or gold bar which designates if the gamer has an Xbox Live Silver or Gold superscription. If the gamer is part of the Xbox 360 Launch Team, the top bar will also have additional text stating "Launch Team" in the background. Third party sites allow users to post a rendered version of their Gamercard as a small Flash applet or JPEG image on any website or Internet forum.

Similarly, Mac OS X users can download widgets that display their Xbox Live Gamercard within Mac OS X's Dashboard. These can be downloaded onto any Mac with OS X 10.4 or higher via Apple's widget download page.

There are four Gamer Zones; Recreation is for casual gamers, Family is for family-friendly gamers (without profanity, etc.), Pro is for competitive gamers who enjoy a challenge, and Underground is for no-holds-barred gaming where anything goes (as long as it does not violate the Xbox Live Terms of Use). However, in practice these gamer zones are only displayed on the Gamercard of the player, and don't tend to impact on the gameplay experience or the matching of players in online games.

TrueSkill

TrueSkill^[17] is a ranking and matchmaking system premiering in the Xbox 360 live services. Developed at Microsoft Research Cambridge (England), the TrueSkill ranking system is now used in over 150 titles for the Xbox 360^{[citation needed]}. It uses a mathematical model of uncertainty to address weaknesses in existing ranking systems such as ELO. For example, a new player joining million-player leagues can be ranked correctly in fewer than 20 games. It can predict the probability of each game outcome, which enhances competitive matchmaking, making it possible to assemble skill-balanced teams from a group of players with different abilities.

When matchmaking, the system attempts to match individuals based on their estimated skill level. If two individuals are competing head-to-head and have the same estimated skill level with low estimate uncertainty, they should each have roughly a 50% chance of winning a match. In this way, the system attempts to make every match as competitive as possible.

In order to prevent abuse of the system, the majority of ranked games have relatively limited options for matchmaking. By design, players cannot easily play with their friends in ranked games. However, these countermeasures have failed due to techniques such as alternate account(s) and system flaws where each system has its own individual trueskill rating. To provide less competitive games, the system supports unranked Player Matches, which allow individuals of any skill level to be paired (often including "guests" on an account). Such matches do not contribute to the TrueSkill rating.