City of Heroes has had some interesting issues with its gameplay, involving a character named Twixt using some tactics which made everybody hate him.
Several years ago I happened to be seated next to the designer of City of Heroes at an event where he won something. He was a pudgy guy, wearing big round glasses, with a white city of heroes t-shirt and a blue cape on. We got into a conversation about his game, and I asked what it was that made it compelling, and he said that it's every kid's fantasy of being a superhero, and it was very obvious that he'd based the game's design on his own. I asked him if City of Heroes is compelling as a pure abstract game, and the interesting response was that he didn't understand the question. After a few minutes of conversation he got what I was asking, and his answer, which really perplexed me at the time, was that it was a good question, but he didn't know.
Consider a game with the following semantics: You sit, unmoving, for two hours, with no user feedback, no buttons to push, nothing, completely passive, while the game plays out in front of you, exactly the same way as it would for anybody else. This sounds like a terrible game, but it's exactly what movies are, and movies are very popular and get little criticism that they're terrible games.
The Twixt problem was caused not so much by any one person behaving unreasonably as the game engine having a problem. There's a battle tactic which is quite effective but has the effect of wiping out an enemy without even giving them a chance to play, making it not much fun for them and it doesn't even get much credit for you. Because City of Heroes is more fantasy than game, players have a convention of not using this tactic, because that maximizes the fun of play. This is done at the expense of an individual's success taking the game as a sport, but since the game isn't a sport, people don't worry about that too much. Real sports don't involve dressing up as superheroes (except for figure skating, but that isn't a real sport). What really should be done is that the rules should be modified so that the particular tactic isn't so nasty. It's a general rule of game design that all players should get a chance to play and have fun, even if they aren't very good, and tactics which allow a better player to win without the weaker player even having a chance to try to retaliate are no fun.