http://rosettacode.org/wiki/Category:Programming_Tasks http://rosettacode.org/wiki/Category:Programming_Tasks This site has a lot of interesting tasks in many

http://rosettacode.org/wiki/Category:Programming_Tasks http://rosettacode.org/wiki/Category:Programming_Tasks This site has a lot of interesting tasks in many languages. "100 doors" and "24 game" are good starters. "Minesweeper" (text-based) is a little more involved, but it might be what you are interested in. Sudoku games and solvers are lots of fun. Making a text-based chess or go game (no ai) could also be an interesting challenge. https://github.com/alexch/learn_ruby https://github.com/alexch/learn_ruby has some good challenges for Ruby, but I'm sure they can be done in other languages.