no Japanese please, I honestly watch too many of them. But I want a drama that is intense and dark I don't want the ending to be too sad but I want throughout the drama to be more serious and be interesting 

Dramas I've Watched:
Signal
Bad Guys 
I Remember You 
The Girl Who Sees Scents 
When a Snail Falls in Love 
You're All Surrounded 
Mrs. Cop 
Healer 
The Master's Sun 
Pinocchio 

Dramas I Haven't Seen: 
Love Me If You Dare 
City Hunter 
Pied Piper 
I Hear Your Voice 
Missing Noir M
Special Affairs Team: Ten

most of the OCN dramas
Evil Minds
Iljimae
Hwayi: A Monster Boy

and I know you said no Japanese dramas, but if you haven't seen it yet Daisho is the epitome of intense and dark.
Signal
Love Me If You Dare
Cruel City
Punch
My Beautiful Bride
Scandal: A Shocking and Wrongful Incident
Bad Guys 
Cruel City
Bad Guys
Signal

Basically most of the OCN dramas
korean drama white christmas is my fav. It is a bit dark and another korean drama gap dong, it deals with serial murder,

taiwanese drama bumped of lovers was extremely dark but it was a bit slow.
Gap Dong
Remember – War of the Son
Korean:
Time Between Dog and Wolf
The Village: Achiara's Secret
Liar Game
The Bridal Mask
I second Gap Dong, Bad Guys and Cruel City. 

Chinese:
Love Me If You Dare