Does anyone know where can I get prolog source code for games like: connect-4, Hearts, etc.

Are you a masochist?

I''ve used prolog myself, and I can tell you that the only type of game (besides rudimentary stuff like number guessing, and maybe tic-tac-toe) that can be reasonably easily made in prolog is the text-based rpg. Prolog is a great language for things like sentence parsing.

If you still want to make Connect-4 or Hearts in prolog, then you''re going to be on your own. Sorry.