The sisters are not evil they are misguided, the story will unravvel itself to you as you begin to play, and you will see how rapture fell from glory. The game is quite hard though so choose the difficulty wisely.
The storyline is amazing and remember to save your game lots and pick up audio diaries.
As far as violenc is concerned, if you have played resi 5 etc. It should be no real shock, some bits will make you jump, as they have slightly more intense environments but as far as that goes its about as much as you'd expect from a cert:18. Infact the little sister stabbing bit is probably the most violent
Epic, that your a girl that plays those games
Hope this helps
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