Microsoft has announced that starting June 1st, all Xbox Live Arcade games will be required to have 400 Gamerscore and a max of 30 achievements. This is an increase from the previous 200 Gamerscore requirement and max of 20 achievements. In addition, games launched between April 1st and June 1st will have the option of using either system.
The rules for DLC are also changing. In the past, developers were able to add 50 Gamerscore and 5 achievements per quarter, a maximum of three times, for a total of 350 possible achievement points and 35 achievements in Xbox Live Arcade games. The new rules will allow 100 Gamerscore and 8 achievements per quarter, a maximum of four times, bringing the potential total for XBLA games up to 800 achievement points and 62 achievements.