kids-crypto
There are 2 repositories under kids-crypto topic.
ruppde/euli_treasure_hunt
Euli is not a computer game but a tool which helps you set up a real life treasure hunt
ruppde/crypto_puzzles
Crypto Puzzles is a tool and library to provide a bunch of functions for encryption or pseudo encryption as puzzles or brain teasers. Awesome for kids but some puzzles are also a challenge for adults.