Xbox 360 slim modding

Hello Everyone I have purchased modded Xbox 360 slim (which I doubt it is modded or not) and they had installed many games on the hard drive.

I don't even need to insert any disc to play the game. Games are installed on my Xbox, when I launch they work perfectly.

My games folder looks like that:
http://postimg.org/image/yjr0oujml/

And my dashboard looks like:
http://postimg.org/image/f4clw22et/


But I am very curious to know how they installed games on it. As of my...

Xbox 360 slim modding