Thanks everyone for all the feedback, everyone. Based on some of the comments in these reviews we've updated our site with 'guest passes,' just a way to post scores without going registering a full profile.
We went with a much more casual approach this time... something you could pick up and play a round within a couple minutes without committing too much involvement in the game.
Mooble is a Flash version of the old Bulls and Cows/Moo/Mastermind type of codebreaker game. A 4-marble code is generated from 6 possible colors. You get 10 attempts to break the code. Each attempt is scored with a series of small white and blue marks. A white mark means you have a correct color in a correct position. A blue mark means you have a correct color in an incorrect position.