Dokgo's story is set in the same universe as a few other stories written by the same author. The stories are Dokgo, Tong and Blood Rain, all of which have the same artstyle and are pretty much about the same thing - violence.
Violence is the main theme of Dokgo, but more than just one definition of violence it shows many kinds of ways to how it can be used. Some keywords to as what words pop up in your head whilst reading Dokgo are Power, Subordinance through fear/respect, Anger and revenge.
The artstyle of Dokgo is very characteristic. It's very simplistic, unrefined and has dull colors
to match it. A major drawback of this artstyle is the limitations of using it. This means that many faces become very similar whenever 2 characters have similar hairstyles. This wasn't too much of a problem in Dokgo as it was in Tong due to the low number of distinguishable characters.
The story is great, a righteous and smart but naive older twin-brother who got murdered is being avenged by his younger brother - with the method the younger brother knows best. The goal is very tangible as this is a realistic story. The entire story takes place within one city primarily in a school or close by.
What's interesting about the main character Kang Hyuk (Dokgo) is that he plans out his moves and measures his opponents as to not make any mistakes. He shows that the only powerful thing about him is not only his ridiculous fighting power, but rather that his head is sharp and that he has experience. Hyuk is very perceptive when it comes to people, noticing inconsistencies in their behaviour when they're under pressure. He also shows that he's someone to be respected through his actions rather than feared.
The main protagonist plays the role of the "king who seeks confirmation". A character seldomly used to this extent, but who always plays the role of the accomplished, smart ruler who never stops trying to advance further. This can be seen where he wants to fight Dokgo but doesn't get to (Why does he want to fight Dokgo?), it can be seen when he's planning to take Kang Hu down by sending a few guys at once, rather than destroying him from the start, and finally when he tries to make a devilish scheme towards the end by putting Dokgo in a situation where he has multiple choices that all rely on sacrificing something.
Overall Dokgo is a great manwha, but it's definitely not for everyone. It has setbacks in its artstyle, and some characters do get overlooked a bit too much.