Rare game developer Nick Burton spoke at a developer conference this week about the revenue stream of downloadable games.
Speaking of Live Arcade games, which sell putatively for "points" on Microsoft's proprietary online network, he said, "[They] tend to sell for a long period of time. ... You don't tend to get the same sales with Live Arcade that you do with an on-shelf product."
After an initial sales surge, Barton continued, sales can baseline to several hundred downloads a day. "So you have a guaranteed - small, but still reasonable revenue stream that's constant."
That purchasing trend well explains Microsoft's pattern of releasing one arcade title per week, so as not to dilute the initial high-download "grace period" the arcade-oriented and classic titles enjoy.
Source: Ars Technica