Everything! The Java theory has been reworked and reorganized so if you read the first edition you might recognize a few of the words to be similar but all the games are new. Even the Snake and Pong games which made an appearance in the first edition have totally reworked code now.

This second edition goes much deeper than the previous, into crucial topics like object-oriented programming and goes even further to cover more advanced topics like Java design patterns, loading game levels from files and Java collections.

More game specific topics are covered as well. Collision detection, physics and huge scrolling game worlds using a movable camera are just some of the additions.

Also, more Android topics are covered, including handling different screen sizes/resolutions and input with multiple fingers. And as you would expect if you had read the first edition, everything is put into practice using a game.

It is hard to know which topics should be highlighted in this summary of contents as so many are covered and I urge potential readers to read ahead in this chapter to see the wide range of games we will build together and then look at the table of contents to see the full scope of the Java topics you will learn at the same time.