One of them is kind of a bad example anyway (while controlling the character, you don't explicitly do anything morally reprehensible), and to name it would spoil it.

The other is De Baron, which I just played last night. In it, you play a lumberjack who has to free his 12-year-old daughter, who has been kidnapped by the baron for possibly immoral purposes. I can't do much better than the author's note:

"The Baron" is about a tragic and possibly shocking theme. Therefore, it is not appropriate reading for children; I advice an age limit of at least fifteen years. In addition, anyone who does not want to be confronted with fictional misery would do better to avoid this story.

For the Spring Thing competition, wherein you will have to read a given number of works in order to be allowed to vote, this may mean that you will have to give "The Baron" a one when you decide to avoid it for this reason. Don't hesitate to do so. I would much rather have a one than a reader who reads on against his or her wishes.

Also, from the in-game note:

"The Baron" is not a traditional text adventure. There are no puzzles to solve, and you cannot win or lose. It is quite literally interactive fiction, not a game. The aim is to experience the fictional world and its disturbing themes as intensely as possible.

It's a terrific use of medium, it's really very well-written, and it's very, very dark. The upshot is that, on your way to saving your daughter, you encounter a number of obstacles, and how you have the lumberjack deal with each may end up having you sympathizing in places you don't want to be. (Irrelevant caveat: the author's first language is Dutch, so if you play it, don't be too thrown by the hints of non-native speech. They aren't overwhelming, but they stand out all the more when they do pop up.)