I need to make sure of this when I get home (at work now), but :
When you're playing a game, to the right of the game itself is a value for "Score to beat". That keeps changing every game I play no matter if the score I just got is lower than the previous or not.
I also believe that on the main page, the column/cell that says something like "Hoopsfan with a score of 50" keeps changing as well. But only for the Darts game so far. The default games keep their values from what I've seen.
I'll double-check when I get home. Maybe I'm not understanding the functionality.
*UPDATE FOLLOWS*
Arrrgg... stupid mistake on my part. I had "Highscore type" set to "high" instead of "low".
Hopefully flipping that will solve the issue...