This is what's included in this package, straight from the Steam store page:

"Ever wanted to see how the popular Hacker Evolution games were made?
Here is your chance with this package which contains all 3 Hacker Evolution games and their source code:

Hacker Evolution (game + source code)
Hacker Evolution Untold (game + source code)
Hacker Evolution Duality (game + source code)

The 3 source code projects will compile and run from within Visual Studio 2010 and are written in simple to understand C/C++. Upon purchasing the source code you will also receive unlimited support via email directly from the lead developer."

If you already have the games, only enter if you intend to use the source code for learning or practicing programming. If you have one or two of the games, use your own discretion, just remember Steam Gifts says you should generally not enter if you have part of a bundle, but I'm not going to check the winners before sending.