MSDOS 5 used to come with QBASIC. Nibbles and Gorillas were great games and they included all the source code.
I used to play Gorilla's all the time when I was a kid. That was how I learnt about angles. My Dad drew a picture for me "This is 90 degrees, This is 45 degrees" it used to sit beside the computer.
I learnt a lot about programming from the DOS environment come to think of it. Our home PC used to have a text based menu program it would boot into. In order to add a program to the menu you needed to edit it, using something like a markup language. My Dad used to sit over my shoulder and talk me through adding programs to the menu.
