Microsoft has acknowledged a technical problem currently affecting the Xbox Games Store.
A large and increasing number of titles - reportedly over 1000 - have inexplicably disappeared from sale.
Xbox Live Indie Games are among those most affected, with the XBLIG store's total available game count having dropped from over 2000 down to a little over 900 titles.
Microsoft has told Gamasutra that the disappearances, affecting stores both on Xbox and online, are a 'glitch' and it is working on a fix.
"We're aware there is an issue affecting the Xbox Games Store that has temporarily removed some content including Xbox Live Arcade and Xbox Live Indie Games titles," said an MS rep.
"This is a technical glitch and we're working to fix the issue as soon as possible. We apologize for any inconvenience."
Xbox Live Marketplace was renamed Xbox Games Store late last month. Microsoft rebranded the online marketplace as part of a wider revamp of the Xbox platform ahead of this November's Xbox One launch.