How to create the sequel of a game

During these days I am playing with Box2D to create the sequel of SamePhysics.
It was my first Box2D game (you can download the source code here), people found it funny so I decided to make a sequel to improve some features I missed in the original game.
Since it’s my first sequel, I had to make some considerations before starting to code. That’s what I want to share with you.
1) Choose wisely which game deserves a sequel
This is the first thing, and the most obvious one. If people did not like the original game, probably they won’t like the sequel. Or, even worse, they won’t even look at it. With two sponsors, ranking higher than 3 and 3.5 respectively on Kongregate and Newgrounds and more than 2.5M views, we can say people liked SamePhysics
2) Fix issues according to the feedback
You don’t upload a game to Kongregate just to make it spread virally, do you? The most interesting thing about Kong is the qualified feedback players give to the game. The aim of a good sequel should be improving things people liked, and reducing things people did not like.
In the original game, one of the major flaws was the collision detection. Using the contact listener class included in Box2D, I was be able to see two boxes as “colliding” only if they collided for real in the physics world. Too bad the sprites on screen are just a visual representation of such world, so if two of them aren’t touching because there are, let’s say, two centimeters of empty space between them, there’s no way to show such a tiny distance on the stage. At 30 pixels per meter, I would need 0.6 pixels to show two centimeters, but I can’t do it.
Look: [...]
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