Them dern mini-game projects

I experienced flash for the first time (well using it anyway) in class during our mini-game projects.  I finally realized how complex computers are.  I always knew there were codes and I figured those little green plates in computers and video games kinda worked on magic.  Well I knew it wasn't magic, but thinking about how it worked always slipped right past my mind without any comprehension.  I can't imagine how complex and long of a list of codes big fancy games have.  Although glitches and hacking seems to make more sense, as does fixing a glitch or blocking a hack.  The life of a game designer must be rough, spend all that time on making a decent game and then out of the blue... BOOM hacked, or people have found several glitches you had overlooked.  My main question now is: How do these codes and random assortment of characters create the stuff it does?  If any smart people stop by this blog it would be nice for a legit answer.