Crystal Dynamics has told Eurogamer that Lara Croft and the Guardian of Light will be an Xbox Live Arcade exclusive for at least a month.
Brand director Karl Stewart said the exclusivity period was down to the inclusion of the game in Microsoft's Arcade of Summer line-up.
PS3 and PC versions will follow a month after in September.
"The agreement with Microsoft is, in order to participate in their hugely successful Summer of Arcade promotion, there is a window of exclusivity. That window of exclusivity is a set four weeks," said Stewart.
He added: "As with all arcade titles, irrespective of platform, you have to go through your submissions before they agree and approve a date.
"Unlike a disc based title where we can pick our window, you have to go by what the first parties approve and give you a date, to make sure you're not coming out on the same day as five other titles. They like to manage the release window accordingly."
Lara Croft and the Guardian of Light releases on August 18 for Xbox Live Arcade.
There's a full interview through here.