One feature of video games I like that I don't seem to see as much as I'd like lately is the ability to fail without a simple game over or restart. I just think that is really entertaining to make a bad choice or just generally screw up in a game and be rewarded with the game changing in some way that is meant to make me feel guilty. It sort of bothers me when I see the lazier side of this, like in the first Assassin's Creed didn't do anything to discourage the player from wanting to kill civilians, so attacking them just drains the player's health. I find it way more interesting when a game predicts the bad behavior of its players and responds to it in a unique way. A good example of this is getting swarmed by angry cuckoos in Zelda games.
This phenomena used to be typified by the phenomena known as the “bad ending.” If the player doesn't do everything right, he or she is rewarded with a game ending in which things just don't work out. It is a neat way to use the interactivity of a game to alter a story, and sadly it doesn't happen as much lately because stories are so set in stone. The only modern example of the “bad ending” that I can think of is the ending of Mass Effect 2 in which everyone, including the main character, die. Sadly, the success of Metal Gear Solid's movie-like story structure has led to it becoming the norm. Granted, that approach has the advantage if the writers have a strong story, but it really should not have been seen as the only way to make a game.
One of my favorite “bad endings” is the one in Streets of Rage. After playing all the way to the final boss, the crime boss Mr. X, he offers the players to join him. From here, the players can refuse him and beat him down to get the “good ending,” or accept his offer and get sent back a few levels before fighting all the way back to him to beat him again and get the same ending. It works the same way in single player, but there is an extra ending if one player chooses to join and the other refuses. This leads to a death match between the two. If the player that chose to join wins, then chooses to refuse to join the second time Mr. X asks, then the player will kill Mr. X and take his place as the gang leader. The player is then treated to a credit sequence in which their character sits in the boss's chair and laughs maniacally.
Streets of Rage 3 didn't have such an evil ending, but it did have a couple of interesting failure endings. For example, if the difficulty is set below normal, the game is cut short, with the heroes defeating a Mr. X, seeing that he was a robot, and basically just going “what the fuck?” The robot then tells to step up and play the game on a real difficulty level. If playing on a higher difficulty level, the level after that has the player attempt to rescue a general before the poison in the room kills him. If he isn't saved the player is taken to an alternate final stage and gets another bad ending. If he is saved the player is taken to the actual final stage and fights the real final boss. During this boss fight a timer is counting down, and if the boss is defeated in time, everything is alright, but if not the player gets an almost good ending in which the enemy is destroyed, but his bombs go off and the city is fucked.
There are some games that I forget have multiple endings. I played the original Resident Evil so many times that I basically know exactly what to do when I play it, so I honestly don't know the particulars of how to get anything other than the best endings. Obviously, not getting the MO disks to free the other main character means that they will not be saved, but other than that the only other thing I know affects the plot is whether or Jill waits for Barry to return with rope after the fight with the snake. I know that Barry and Rebecca can die in Jill's and Chris's game respectively. The funniest ending, though, is the one in which the player is completely incompetent and doesn't kill the Tyrant. The self-destruct sequence isn't even activated, so I guess there would still be a bunch of zombies and BOWs wandering around the woods, too.
So, at this point pretty much everyone knows that Castlevania: Symphony of the Night has a fake out ending in which the player kills Richter, and there is actually a whole inverse castle to go through. What I believe less people know, or at least less people have bothered to get, is the “worst ending.” To get this ending, the player has to obtain the glasses from Maria that allows Alucard to see what is controlling Richter, then kill him anyway. It is just a hilarious dick move on Alucard's part, and in the context the ending is incredibly awkward. Maria asks Alucard how Richter is, and when he says “I'm sorry” it almost sounds sarcastic. She then tells him that she won't stop until she finds out what was wrong with Richter, to which Alucard basically says “yeah, good luck with that, lady. Later.” What a bastard.
While Deus Ex: Human Revolution caught some flak for not being as malleable as its predecessors, and the main plot had only a little variance, there was actually a lot small, interesting ways that the player can affect future events. For example, if the player dillydallies too much before the first mission, most of the hostages, which normally can be saved, will be killed before the player even gets there. This is a good way to start off the game with people being pretty damned angry with Jensen. Later, there is a part in the game in which you can accidentally kind of ruin a guy's life. He shows up later blaming Jensen for his troubles. In my play through I told him I was sorry and that I'd help him get a new job and what not, but in my friend's play through he told the guy to fuck off and the dude pulled a gun on Jensen, a thoroughly suicidal choice of action.
Basically, I like games that reward incompetence or dickery with guilt and shame. It is just funny to me. The main reason that I find Heavy Rain entertaining is because it allows the player to be completely worthless and ineffectual, but the game continues on anyway. For example, I played Shelby as a complete coward, and it was hilarious in a really sort sad way. After seeing the jerk boyfriend go into the dead kid's mom's apartment, I walked up to the door, listened to her get beat up for a bit, knocked on the door, then after he came and yelled at me, I walked away instead of kicking in the door and fighting him. When the convenience store was being robbed I hid behind a rack of chips and watched as the robber murdered the clerk. The next time I saw the dead kid's mom her face was all bruised up from having been severely beaten. I'm a monster.