In a choice-based game like Detroit: Become Human, every decision taken by the player is important. With a multitude of outcomes available and even the smallest of mistakes able to make everything crumble in the long run, the game doesn't exactly make it easy to keep everyone alive for a good ending.
To get the best ending, everyone from the core group of people needs to stay alive. This includes every major character in Markus', Kara's, and Connor's storylines. Markus will want to keep North, Simon and Josh alive, while Connor only needs to worry about Hank. Kara needs to look out for Jerry, Alice and Luther. To get the best possible ending, here are a few commonly made decisions that count as mistakes and how they can be remedied.
10 Not Recruiting John
During the Spare Parts quest where Markus and a few others raid a CyberLife plant for some parts for Jericho, they'll encounter an android security guard known as John. John can actually be converted into a deviant, and he'll eventually want to join the others in Jericho. However, Simon opposes the decision.
As Markus, you should choose to take John with you. If he's recruited, he'll save Markus' life during the Freedom March and prevent Simon from sacrificing himself if he happens to be alive during that specific quest. John isn't part of the required characters to keep alive, so if anything he's a way to make sure both Markus and Simon survive.
9 Shooting Simon
During the Stratford Tower mission, things are bound to get hairy. As Markus, you'll first and foremost want to avoid engaging with the security guards at all costs. This ensures that Simon survives the first part of the mission.
However, once you make it to the roof, Simon might be wounded and Markus will be given a choice whether to leave him behind or kill him. Although it might seem merciful to kill him yourself, he should be kept alive. Later on, as Connor comes to investigate, make sure not to go to the roof to ensure Simon is able to hide and survive the whole ordeal.
8 Failing To Play Dead
After Kara and Alice successfully make it to Jericho, the whole place will end up getting raided. Multiple characters will be at risk at this point and while it's pretty straightforward to keep most people alive, Kara and Alice are at the greatest risk here.
When the two of them fall to the ground after being chased, make sure not to surrender. If they surrender here, they'll be sent to the recycling plant, which will force the player to sacrifice Jerry to ensure their safe getaway and therefore abandon the perfect, good ending. Instead, play dead in this part, and the two will successfully escape danger.
7 Not Keeping The Bus Tickets
There are many choices in the game that play on ethics and conscience. However, the moral of the story with Kara and Alice is that sometimes, cheating and stealing is justified when survival isn't guaranteed. The best example of this is the faithful mission just before boarding a bus, where Kara needs to acquire a ticket.
A family will accidentally drop their tickets to the ground after an interaction with them, and Kara has the choice to either keep them or return them. Despite how wrong it might feel, it's necessary to keep these tickets and board the bus.
6 Not Hiding Luther And Alice Upstairs
While Kara, Alice and Luther are hiding in Rose's safehouse, the police will eventually come knocking at their door. Kara will only have a short period of time during which they can hide any evidence scattered around the room, pointing towards androids being in the house.
The most important part, however, is to make sure that Luther and Alice hide upstairs in the house and nowhere else. Otherwise, Luther will be found out and he will sacrifice himself for Kara and Alice.
5 Failing To Befriend Hank
Connor is probably the easiest and most forgiving character to play. His mission is mainly to become good friends with Hank, which shouldn't be too big of a deal. This involves making choices that reinforce Connor's humanity, but might make Amanda question Connor's stability and efficiency.
Moreover, make sure to look around carefully in Hank's house when entering the place for the first time. His dog Sumo and the photo of his dead son on his table are particularly important factors that will come into play later on in the game.
4 Accepting The FBI Deal
At the end of the game, Markus and his friends from Jericho will find themselves in a pretty tough spot against Detroit's police forces. The pressure is definitely on, and it's made evident to the player that it will be difficult to stay alive as the androids are outnumbered.
That's why the FBI agent's offer might seem tempting, but it should be refused. When Perkins calls Markus over, make sure to have Markus decline his offer and insist on staying with these friends until the end.
3 Sacrificing Someone At The Border
One of the more high stake missions for Kara, Alice, Luther and Jerry is the border control just before entering Canada. It might be extremely tempting here to do something radical, such as behave in a suspicious way or even use Jerry or Luther as a sacrifice.
No matter what, don't sacrifice anyone here. Everyone will successfully stay alive if the quest with Markus is going accordingly at the same time. The border control agent will take pity on the androids and allow them to pass through.
2 Failing To Remain Fully Peaceful
Markus' movement is the most crucial part of the game, because it's not just his and his friends' survival that depends on it, but also that of Kara's and her friends. As such, if Markus' movement isn't peaceful the whole way through, the player will struggle to keep everyone alive between these two missions.
During the CyberLife store raid, make sure to emphasize peace instead of violence. The same goes for the Freedom March, where Markus should stand his ground but not become violent. Finally, at the end, despite being outnumbered, make sure Markus and his friends do not take up arms.
1 Failing Connor's QTEs At CyberLife Tower
Markus' peaceful movement at the end will only succeed if Connor succeeds at his mission at CyberLife headquarters and has chosen to become a deviant. This is the only part of the game where Connor cannot be allowed to die, so extreme caution is needed here.
The QTEs (quick-time events) will be particularly tough in this part, so make sure to nail them as otherwise Connor will die permanently, which will spell disaster for the rest of the characters. Moreover, if Hank's son's name and dog's name is known, this mission is guaranteed to be successful.