Ok, so i know the little girl looks a bit ghoulish but she's still a little girl living alone in a really bad situation.

And the robot with the drill arm only appears to attack to defend the girl.

So why (reviewing the trailer) is the protagonist so hell bent on giving this little girl the bash?

Because if you harm the Little Sisters, the Big Daddy ( the robot with the drill arm) comes out to kill you. You can harvest the Little Sisters for ADAM which is some sort of resource for the player to use to gain powers. Never played BioShock but read enough about it.

Those girls have been posessed. The protagonist needs the adam mutagen present in girls to purchase gene enhancements. He can either extract all the adam from them killing them or extract enough to make them normal again thus saving them.

You can choose to harvest the girl's ADAM (killing them) or you can heal them (which obviously heals them).

However, the moral issue of killing someone just trying to protect the life of another that will *not* attack you unless provoked is ignored by most.

This. I didn't realize the Little Sisters were (still) normal little girls until I'd met Tenebaum, hence I didn't feel any moral backlash when killing them. It was more of a choice between "get more ADAM now or get less now but wait for them to give me more later"

Not like I needed ADAM anyway, since it was ridiculously easy to play even with the difficulty balance mod.

For me it was moreabout picking the skills I wanted with limited adam. And easy? Maybe for some, not for all. :P

:)

In most games being good can be more rewarding, sure you wont get so much ADAM but you get neat things like ammo, money and stuff...and anyway there isnt THAT big difference between the ADAM gained from rescuing or killing the little sisters (this is from Bioshock wiki so I am not absolutely sure if numbers are correct) if we count the ADAM from teddy bears for each 3 sisters you get 440 ADAM if you rescue them. If you choose to harvest them you get 480 ADAM.

I chose to be good for two reasons. First one is that those little sisters didnt have choice. They were forced to become little monsters that act basically like vultures, and you have powers to set them free from their curse. And the second reason is that I found the good ending to be more satisfying.

Little sisters were easy. You can save them. It is a good thing. Harvesting them was pure EVIL, no matter what.

Big daddys though, there was a problem. At the beginning there were quite hard (hard, vitachambers off and "console" mouse). You have to kill them, but they are same manmade monsters as little sisters. But there is no hope for them, no curing. I was sad beacuse of them.

Well, i can say i put them of the misery, but...

Being good is worth it just because you end up getting the Hypnotise Big Daddy plasmid.

I just can't be evil in games. At first I migth start, if given a choice, as some bad ass character with an attitude, but I always evolve into shining knight if possible.

I can't either... I usually end up being neutral(if at all possible). Both extremes feel horrible in my opinion.

Yeah, chaotic good for life! :(

I had to try really hard to be neutral (but not lawful). Evil is out of my reach.

Ah, that's cool - you can return them to normal.

I just found the trailer to be a bit odd cause you think the poor kid has it hard enough without going after her with a wrench.

And the big robot protecting the kid is only doing the right thing.