It's hard being a protagonist. You make countless sacrifices, battle through countless levels, die countless deaths, and for all your hard work, you're still never going to be as cool as the villain. It's surprising how few goody-two-shoes ever make the transition to bad guy status and take advantage of its perks: cooler costume, army of minions, a chill flying death fortress to hang out in while those sucker heroes come to you.
But when they do, it's always a big event. We're talking about genuine good guys (playable protagonists) that somehow end up on the opposing side (antagonists that need to be taken down). Here's our list of the 8 greatest heroes-turned-villains in videogame history.
8. Alex Mercer (Good Guy: Prototype; Bad Guy: Prototype 2)
To be fair, whether or not Alex was ever "a good guy" is up for debate. He spends most of Prototype slicing & dicing anyone who has the misfortune to wander onscreen, and the rest of his time is occupied by learning new freakish nightmare powers in order to craft himself into a more efficient murder engine. Is it wrong to feel sorry for the enemies in a game? I'm hesitant to ask, because it feels like if Alex could reach out of the TV screen and kill the player, he would (I hear Radical Entertainment is working on that tech for the sequel). I wouldn't be surprised if the original idea for this game had you controlling the US military and was called The Story of the Horrible Monster No One Could Stop And Who Ate Everyone The End.
However, in the gap between developing Prototype and starting work on the sequel, apparently one Radical employee took a look at this walking wall of fleshy horrorblades and said "Hey, our hero looks way more like a Silent Hill villain than a protagonist. Let's just run with that angle." In Prototype 2, you'll be playing as a new character, a war veteran whose his wife & child were killed by Alex's rampage in the first game. Your new goal is the execution of your former main character. The working title? Prototype 2: You Deserve This.