While Mark's situation was understandable, and Connor took his objections way too far, appropriating corporate funds for private use, even if it's to save somebody's life, is called "embezzlement".
And also there's the less mundane crimes of reanimating the corpses of dead employees. Some of whom were murdered, and Broadside covered them up because the authorities would've discovered the Starling project and shut it down otherwise. Even Rex, the person Mark was trying to resurrect, was turned into a Starling. Despite Mark's best intentions, the ends do not justify the means, and ultimately Connor exposing Mark's crimes was the right thing to do, even if for the wrong reasons.
Brandon's motive for killing the others, according to Word of God, is that he was made to think that he IS Bucky, and thought the others were impersonating his friends and family. That's some very Disproportionate Retribution, especially with how brutal his methods were, so what does that say about what the real Bucky would do in his place? Bucky has probably realized this implication as well, which would explain why even looking at himself in the mirror makes him feel sick; he's terrified he would do the same. Not helping is that Husk seems to be actively trying to convince him that this would be the case.
Failing Olive's minigame three times results in a scene where Bucky gets teleported to a brand new location: a lake with Olive's drowned corpse and a copy of Bucky silently walking away. While it's meant to be a parallel to Brandon Lester's murder of Olivia Finch, who are the voice actors and Starling/Dweller counterparts of those characters respectively, the scene takes a sadder turn when one remembers the context of what has just happened. The fastest way to fail Olive's minigame is to punch her. Repeatedly. With arms strong enough to knock down coconuts from trees. Just like how Brandon killed Olivia, there's a good chance you just made Bucky kill one of his friends when he called upon you to help save them. Remember, Bucky reacts negatively for going down the true route, with the murderer stuck in a version of his "costume". Him "recreating" one of the murders is likely contributed to his decline in mental health that leads to him killing himself at the end of the game.
Additionally, an eyeless Olive follows Bucky throughout the other minigames if hers was failed beforehand. It's probably meant to be Olivia, but who's to say it's also not symbolic of Bucky's guilt over something he did not do, whether it be Olivia's death by Brandon's hands or Olive's death at yours.
