Hi 11bit, I downloaded your game a few weeks ago, before Mountain Lion and Game Center were released. Once it had been released and I updated my Mac (New Mac Book Pro Retina Display), I didn't play again until I had no internet connection. Apparently all my achievements were being achieved and saved, but for my surprise, when today I connected to the internet and started Game Center I discovered none of those achievements had been saved. They all disappeared. Do I have to get them all one by one again?
Also, I'd suggest you solved a problem when checking achievements in-game. Custom cursor for game just turns back to normal, and doesn't get back to custom after closing achievements window. It's pretty hard to play with normal cursor and it feels lazy to re-start the game every time I check the achievements.