Probably laughing maniacally while mowing down animals and pedestrians on Carmageddon, or nuking the crap out of everyone on Civilization II. XD I'm oldschool like that. Also, on Rise of the Triad (another oldschool PC game!), there's this one enemy where if you shoot him a certain number of times, he'll drop to his knees and beg for his life. Naturally, I'd try doing that every chance I got.
In Skyrim, when I was heading to get my dragon breath ability, I met an Ice troll and ran away. There was this praying lady at this stone thing. And I led the creature to her. It killed her and I took care of it after. I didn't technically kill the NPC, so I didn't have any problems taking her equipment. She had Dragon Scale Armor. I wasn't going to restart the game so she would live. I liked her stuff. It's still funny hearing a town guard mentioning I have nice armor, but he can't prove I killed a character in the game because of the Ice troll.
I know you said GTA Killing Sprees do not count, but in San Andreas I inputted the hover car cheat, planned to pick up a hooker, park in the middle of the river.... let her pleasure me, and waited for her to get out so she would drown.... god I was sick as a teenager.
even though I was trying to play as a good character in Skyrim I did a few bad things like killing a housecarl (not lydia) to start the 'Call of Boethia quest'. And In Dragonborn, there were these Thalmor who stole a map to a Stalrhim source. I intimidated them to give it back, expecting a fight and they agreed to leave instead. So I went up and massacred them all.
In Overlord I came across a load of Gold and I had the choice of giving it to some poor people or keep it for myself. Of course I gave into greed.
In Fable 2 you can randomly enter other peoples games and mess with their world, in which changes are permanent. I entered this guy's world who happened to be at his house. I killed his wife. I was waiting to do that since day one lol. Also in Fallout 3, in Tenpenny I killed all the guards and stripped them of their clothes and put them in obscene poses in the stairwell. I'm a monster. I'm this close to killing my wife (Lydia) in Skyrim. I married too early!!
In Sims 3, the maid kept stealing food from my fridge and then leaving the trash on the table.
So I befriended him to the point that he would move in with me. Then I built a room in my basement, complete with giant floor to ceiling windows, put a rotting plate of food on the floor, lured him into it and locked him in. I came down and watched him every day as he repeatedly tried to eat the rotting food only to throw up all over the floor and eventually starve to death.
I had a haunted basement from then on but that son of a bitch stopped stealing from my fridge.
In Baldurs Gate: Little orphan girl asked for help to get her kitten out of her mean uncles house. Went in, discussed the matter with her uncle and agreed to kill the cat instead. Afterwards went out again to brag to her about it. Thats ridiculously evil. I felt bad enough to do an instant reload...
on oblivion i went to that really tall cliff edge where people are meant to commit suicide then i told the annoying cunt that is the adoring fan to go home and he made a bee line for his home straight off the cliff.
otherwise i have given hours of abuse to people on cod and halo for just being annoying and have spent so much time with my friends blocking people in corners for entire matches, being a dick is too fun.
It's really hard to decide what the most evil thing I've done in a video game is. I'm a horribly cruel player. So, I'll just list the three most evil things that I remember doing.
In Skyrim, I downloaded the killable children mod, killed Braith, then dragged her body out into the middle of the street just to watch people's reactions. I killed then killed the rest of her family because they kept bitching every time I passed by them. I decapitated Grelod the Kind. I also decapitated the Emperor (even though I didn't mean to do it). I would sneak up behind guards at night in Whiterun and slit their throats just to raise my skills.
In Zoo Tycoon, I would also repeatedly put guests into dangerous animals' exhibits and then block them off. It was fun watching them get eaten by dinosaurs and sharks.
In Dark Souls, I killed a merchant for his weapon even though I could have bought the weapon from another person later. I also killed Priscilla. I had cut her tail off first for her weapon, then decided to kill her for the souls. I talked to Ciaran and refused to give her Artorias's soul, then I attacked her and killed her for the souls, armor set, and weapons she drops.
I'd chosen the "Seven Veils" compliment gesture: you do a sexy little dance while saying "Wanna see something special?". So I'd go up to NPCs - especially ones who had just said something nasty about me - and do that, then while they were starting to react, I'd hit R3 to punch them in the nuts.
End of Fable 2. Insanely powerful. Hero to all. But bored.
Systematically killed every one in every village, bought their houses and then charged rent to new tennants, rose all prices in all shops and sat on a throne of blood and coins.
Thrones of blood and coins might sound cool, however the coins get stuck to your clothes and the blood starts to smell after a while. Also the flies. And the buzzing. And the loneliness. Oh the guilt. The nightmares.....
Nuked entire cities throughout the various SimCities, sent entire planets to burn or freeze in SimEarth because I got bored with the current inhabitants and making sure I picked off every last bit of life by hand.
Super long time ago I used to play Day of Defeat with my friend online. There was this one map where all of your teamates would respawn in a cabin. There was only two way out of the cabin and me and my friend just blocked both sides. Our team would always spawn inside and complain. Our names would be "Ghetto Camp Here" referring to the holocaust. My friend and I would also spam in chat Kill the prisoners.
Thinking back, yes immature, stupid, evil. But then again, that was more than 10 years ago . Maybe even 15 years ago.