Cryptose is an addictive cryptogram game with three gritty themes to choose from: Hacker, Detective, and Espionage. Each game you get a random short encrypted phrase (out of a database of thousands), and it's your job to decrypt it. The phrase is encrypted with a simple substitution cipher, meaning that each letter in the alphabet is replaced with another letter (for example, all A's might be replaced with Q's). You start out with the ciphertext, and it's your job to figure out what the plaintext says. To play, tap a letter in the phrase (say, A) and the alphabet will pop up. Then tap the letter you want to substitute A with (say, Q). All As will be substituted with Qs, and your key will get updated. Keep this up until you have decrypted the entire phrase. If you get stuck, tap Hint and a letter in the key will get solved for you. Between games there are interesting facts and quotes about encryption, many of them about cypherpunks and their role in legalizing it for the masses. The game is just about done, about to be sent off to beta testers. It should be in the App Store in a week or two! I will also be releasing an Android version of it in the Android Market about the same time.
Looking forward to this. It goes high up on my "someday" list of purchases. Will probably get it soon after release, as it combines some of my favorite things - puzzles and privacy/encryption/cypherpunk.
I just submitted Cryptose and Cryptose Lite to the App Store! They're both already available in the Android Market.