I wish to teach my nephew who is 12 programming.

He wishes to go straight into game developing.
Is there any open source/shareware java games with graphics front end? I want the game to have graphical front end from the start so all I teach the students is game logic via “if statement”, “Boolean logic” etc.
Typical games I am thinking of are Java Pac man game, java spaceship game, java maze game, java arcade type game however it must have a graphical interface.

Thank you in advance