I bought Super Hexagon on Android a while back. On first launch it asked if I want to enable something called 'Scoreloop'. I refused it at first, and the dialog never came up again, nor did I find anything about it in the main menu. The dialog, however, did pop up after every update to the app, which did make me curious - what does enabling Scoreloop do?
I had to reinstall the game and I enabled ScoreLoop to give it a try.
Now I have a link to "Achievements" in the upper left corner of the main screen. After selecting it you can see the ScoreLoop window, with some (very basic) achievements, leaderboards, your ScoreLoop account (friends, games...), and that's it.
I noticed that enabling ScoreLoop doesn't seem to be retroactive, as I have 0 unlocked achievements, although I have already completed some of the levels. I tried to complete the first level again and still had no effect on the achievements... So I think it's not worth it.
Still, the main reason why I wasn't interested in ScoreLoop is that I wasn't expecting to get a good place in the leaderboards, because this game is hell.