Gamer Points
From Xboxic
Gamer Points are accumulated on your Xbox Live account by getting Achievements during play. Every Achievement is worth a predetermined amount of Gamer Points, as decided by the publisher, but no more than 1000 (not including an extra 250 through downloadable content for some games) for a retail Xbox 360 game and no more than 200 for an Xbox Live Arcade game.
Other players can look up your Gamercard at any time, either from the Xbox 360 Dashboard or online on the Xbox Live Homepage and thus check your current Gamerscore for all games you have played against their own.
Gamer Points have no value other than being able to brag to your friends, unlike Microsoft Points which are used to buy games and other items on Xbox Live Marketplace.
Amount of Points per Game
Any retail Xbox 360 Game is allowed to set a total of 50 Achievements worth 1000 Gamer Points. Some games have fewer points available, such as Condemned: Criminal Origins with 970 or Project Gotham Racing 3 with 900.
Xbox Live Arcade games are allowed to set 12 Achievements worth 200 points in total.
As of February 1st, 2007, the gamerscore system has been given new rules to follow. Retail games must still offer 1000 points, but can add 250 more with expansions or updates via Xbox Live. Already this has proved popular, as the Oblivion Shivering Isles expansion, Marvel Ultimate Alliance and Crackdown have all implemented the extra points for extra gameplay. Arcade games may also do the same, and can add 50 points to the 200 they already offer.
Games which do not offer the 1000 may use Live updates to add the remaining achievements to their games, but these updates must be free.
