In order to gather adam, you need a little sister. To get one, you need to kil her big daddy like in the original. But after you get her, you carry her around until she leads you to a body with adam. When she gets off to harvest it, splicers attack & you need to defend her. Thats the only time she needs defending. She takes no damage while being carried around & for a lot of the time, you don't even carry one around.
After she gathers enough, you collect adam from her by either freeing her or killing her. Like in the original, killing her gets you more.
The big daddies have some new moves, but are similar to the original. The big difference is the addition of big sisters. They're plasmid using ninja versions of big daddies.
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"The Rich are there to take all of the money & pay none of the taxes, the middle class is there to do all the work and pay all the taxes, and the poor are there to scare the crap out of the middle class." -George Carlin