You know what would really make this app amazing (aside from the additions that others already recommended) is offering cloud service like Evernote. For designers on the go or who uses MacBook Air, space for data can sometimes be very limited.

Preview mode would store tinny file images on the HD while linking to the full image file on the cloud. The user can then download the full image file onto their HD if needed and delete off the HD when they're done (original remains saved in the cloud).

The users can also share large image files to others by sending people a link to the image in the cloud. The option to secure access to the image file with a password would also be an option. The option to share an image folder securely would also be amazing. Everything would be perfectly synced between the HD and the cloud. A designer can only wish right?

I'd rather have it running behind the scene or show an icon under my activity bar on the top right corner of my screen rather than seeing it on my dock. They'll get a 5 star if they change that.

I love the game. Though I wish there was a way to adjust the speed of the game with a slider so that that one could really get a zen feel for this game.