I am going to put a Gadget here, just for the hell of it.  This is was a really neat Flash Sonic the Hedgehog game.  Although there are were only six stages, it is was really quite fun (like a real Sonic game), and has had a few different "Cheats" for winning the game with the various characters (winning with Knuckles, for instance, allows allowed you to run "behind" the scenery - although this dosn't didn't seem to grant any kind of advantage, as such.  So, I'm not sure it's a cheat, as such.  But whatever.)

 

Somehow, in the four years that have elapsed since I last looked at the page, the little Sonic game seems to have disappeared.  I suppose I shouldn't be surprised.