One of XBLA's breakout titles, Marble Blast Ultra, has been silently and mysteriously delisted from the Live Marketplace. The game proved popular with 360 owners early in the consoles life and even throughout it, selling well over 700,000 copies since it was released.
The game can still be purchased on GameStop's website as a download code, but in the past these codes have not worked for delisted titles. So we would strongly advise against purchasing them at this time. Downloadable content for the game can still be purchased however, so if you never picked that up now may be the time.
We have contacted Microsoft and GarageGames, the game's developer, to find out exactly why the game has been delisted.
Update: We have received more information from GarageGames Community Manager David Montgomery-Blake which gives a good idea of the reason's behind Marble Blast Ultra's delisting.
In 2009 GarageGames was rebranded Instant Action, the company launched InstantAction.com which aimed to bring more substantial games to web browsers. They met with some success but unfortunately at the end of last year it was announced Instant Action would be shutting down.
GarageGames has since been reformed, but during the time between now and the shutting down of Instant Action many of their IP has been sold off. As such the rights to Marble Blast are gone, which explains why the game is no longer available on Xbox Live.
Unfortunately it's not clear exactly who has the rights, so there is really no indication as to when if ever the game will return to the marketplace.