There are essentially only two operations involved in the encryption of a message: substitution and transposition.
Issue 2
The game Scissors, Paper and Rock (SPR) has a long history. One famous contest took place in the pages of You Only Live Twice by Ian Fleming and resulted in our hero James Bond defeating the inscrutable Tiger Tanka.
Issue 3
According to Francis Bacon, perfect ciphers may be recognised by the following virtues: "that they be not laborious to write and read; that they be impossible to decipher; and, in some cases, that they be without suspicion."