Microsoft — through Major Nelson — today confirmed that the limit for gamerscore allotments in Xbox Live Arcade titles is doubling from 200 to 400. For games that are already on the Marketplace, developers will be allowed to create up to 10 more achievements for a total of 20 in order to meet the new cap. The Nelson blog also mentions that these parameters will be mandatory for any new games on the service.
The new rules take effect completely starting May 31. Games released between April 1 and that date will have the option of adopting either system. DLC will also be affected by the change: Instead of the current limit of 50 gamerscore and five achievements per quarter, that’s been expanded to 100 gamerscore and eight achievements per quarter.