You are ____, an Orc child, who village was overrun by Human and elven scum "adventures" who killed your family, stole all that was in it, and piled all the junk and polymorphed it till it was something useful. You fled into the woods, the only survivor. Now that you have reached of age, it is time to get revenge on those Human and elven scum.
You start out as a simple orc of X class, and you start out by raiding human farms, with just a few farmers with pitchforks, (random wilderness settings) and slowly you build up your Orc and his items so you can take on tougher levels of Human, and eventually, elven towns. Slowly getting from the frontier of human settlements (easy pickings) to the heart where you face towns with captain of the Guards, Wizards, Priests, and castles that you must penetrate and in the center room, get a important encounter, may it be raiding a treasury, killing a prince (who might drop nice items), kidnap a princess, or raid an armory.
One could also kidnap women and children (as Orcs are known to do) and after each "level" or town, there is a percent chance that for each women you capture, you get a 1/2 orc "pet" and if you capture a princess, the percent chance would be for a special pet, say, a Shaman healer or a Orc Bezerker (orcs don't spell well after all).
And at the end, you must take the capital of the Human/elven kingdom, lead by the same Adventures that eliminated your village all those years ago.
Silly Idea i know, but it not the usual bit. ;)