The first "evil" campaign I ever took part in (I was 13) was DM'd by my good friend Mike. Up until that point, I had been DM'ing, and we had ben playing with pretty standard "Save the Princess/Kill the Monster/Defend the Village" type tropes.
Mike had something else in mind. His world was
bleak.
Warring city-states in a blasted wasteland. We were mercenaries who, often as not were paid in
food. The starvation rules were often in full effect, and we were fighting while weakened most of the time.
Our greatest assets were our two spellcasters (Wizards) and our equipment (Good arms and Armor), other than that we were basically screwed at all times (lucky for us, most NPC's were equally screwed).
The city staes tended to be run by Evil Overlords, and pretty much the best result you could hope for was that you had been hired by a Lawful Evil guy, as he would most likley actually pay you what he had agreed. Neutral Evil guys would--often as not--send you away without payment, or would "renegotiate" after you had completed the job. Chatic Evil Overlords would usually try and kill you as "payment"
The jobs we were set on were of the "retrieve my daughter, and bring me her captor's head (she had escaped with her one true love)" , "Burn the fields of The Neighbouring Overlord and bring me his peasants as slaves", and "kill that pesky unicorn" variety.
It was the first RPG where we were constantly
thinking; nothing was guaranteed, trust was a precious a commodity and--though our alignments varied from Neutral down to CE--by God we
stuck together..because honestly, who else was going to look out for us?
I ran into Mike the DM a few years back and told him how great I thought his "Zorbonian City States" game was and he let me in on a little secret...
It was, in his mind, a total disaster.
We were expected to, for the first few levels, engage in atrocities; then as we grew more powerful and saw the suffering being caused, he thought we would start defending the weak and using our position as Mercenary leaders/City State Overlords/Whatever to effect a change for the better in the culture of the city states.
All that happened was we became
phenomenally good at Burning Crops, Enslaving Populi, Assassinating Competitors and Debauchery.
Lesson learned: Don't let 13-year olds run a country
I'm not sure there was a point to this post.