5 - The rest of GamerServices is just plain unavailable for indie developers. Achievements, for example, one of the must-have “services” for any self-disrespecting modern game:

This class and all related methods and properties only retrieve a calculated result for titles approved to access Xbox LIVE Services through the Xbox LIVE Registered Developer Program. For Xbox LIVE Indie games, the properties in this class will not return a calculated result, and related methods will report a NotSupportedException.

In other words, hobbyists don’t get to do achievements. As far as I can tell, you can’t even test these things as an indie developer.

From my blog.

I decided later that night to try and roll my own. I think it's pretty good so far. One self-contained .cs file to handle it all, with callbacks for nice integration into the games that use it.

The webpage (also quite self-contained) isn't that secure yet, and achievements don't have images yet, though they do already have a field for 'em.