I just now picked up BioShock. I have yet to face a Big Daddy, but have been introduced to them via an in game cut scene. Before I engage in mortal combat with one I had a question about the necessity to engage them. I think I remember reading / hearing that you could complete BioShock without killing any Big Daddies or Little Sisters. It's also entirely possible that you can't and my memory is foggy.

Can you complete the game without killing any Big Daddies? If you can are their benefits to doing so? Are there disadvantages for not killing them?

I ask because unfortunately, I generally don't have time to replay games so look to complete them with the best outcome possible. I am very early on in the game so please answer with as few spoilers as possible.

  • 3
    This is unrelated, but since we have another question about it, and you're avoiding spoilers elsewhere and it's easy to screw up, I'll simply warn you now: DON'T KILL SANDER COHEN. Commented Mar 13, 2012 at 18:59
  • @LessPop_MoreFizz Thanks for the tip! I will definitely avoid killing Sander Cohen, whoever that is :)
    – ahsteele
    Commented Mar 13, 2012 at 19:00

4 Answers 4


Other than maybe saving ammo and so on, there is no advantage to not killing them.

There is an advantage to killing them:

You can rescue or harvest the Little Sisters they guard after killing them, which lets you get more powerups. (Not all BDs guard Little Sisters.)

And you do need to kill at least 3:

Two in Haphaestus in order to complete the EMP bomb, and one when you're escorting a Little Sister.


You have nothing to gain and everything to lose by not killing the Big Daddies guarding the little sisters.

The only source of ADAM in the game (the currency you upgrade your plasmids and self with) is from little sisters. You can only get to the little sisters by going through the Big Daddies. Without tonics, plasmids, and other ADAM bought upgrades, your game will be made exponentially more difficult. This is not the way to play Bioshock on a first playthrough. A minimum Big Daddy run is something for another playthrough challenge.

There are no less than 3 Big Daddies you will be forced to fight before the game allows you to continue, so you will have to fight them at some point.

To receive the best possible outcome in the game, you will need to fight the Big Daddies and retrieve the Little Sisters. What you decide to do with them is up to you...


No, it is not possible to complete the game without killing any Big Daddies, as you will be forced to kill some in order to

collect the necessary parts to finish the EMP bomb in Hephaestus.

Not killing a Big Daddy means you won't be able to harvest or rescue the corresponding Little Sister, so you won't get any ADAM for buying upgrades. The only advantage of avoiding a Big Daddy is that they are challenging enemies to deal with, so you save some ammo and health kits by not having to fight them.

However, there are achievements for dealing with all the Little Sisters in the game, and rescuing all of them will give you a different ending, so you'll probably want to kill all the Big Daddies.

  • Probably want to kill all the Little Sisters or the Big Daddies? Is the difference in ending affected by harvesting vs killing the Little Sisters?
    – ahsteele
    Commented Mar 13, 2012 at 19:59
  • The Big Daddies, but yes, there are different endings depending on your choice of harvesting vs rescuing the Little Sisters (I think that's what you meant). Harvesting gives more ADAM straight away, but rescuing them gives you a gift for every third Little Sister you rescue, and the items in those gifts are probably worth more than the ADAM you give up, so it pays off in the long run.
    – hammar
    Commented Mar 13, 2012 at 21:40

Killing big daddies/little sisters give you benefits to make the game easier. If you choose not to kill them then you'll likely have problems with the bosses later.

However, I've not actually finished the game (and just purchased it a few days ago myself) so I can't say definitively one way or another.

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