Tower of God is a Korean Manhwa, or the Korean version of Manga. Except unlike a traditional manga or comic book that is printed Tower of God falls into the classification of a 'webtoon' which is originally published online in full color and is read in one long rolling strip.
Frankly is probably one of the best things currently on the internet. The art is fantastic, the story and setting original, it has great character design with great diversity in that design. The plot has the perfect mix of action, drama, comedy and tension. The plot is complex but the tension is so high that the first time I read it I blew through it so fast I missed things. I've almost finished rereading the entire series and I'm understanding everything much better now.
Since it's in full color and not separated into distinct pages it flows much more like an animation than a manga in some senses. It's hard to express just how good it is if you haven't read it, the plot is deep yet accessible, there are huge shades of gray in the morality of the different characters, almost nothing is black and white.
It's incredibly popular, with the 4th highest rating of any series on mangaupdates. It's proven so popular that the Korean publisher has released it all translated online for free with weekly updates of new chapters here: http://m.webtoons.com/episodeList?ti…
But I prefer the fan translations since I think the website is formatted a bit better and they provide useful translation notes. But to each their own. Fan translations can be found here: http://mngacow.com/tower-of-god/ Once you open a chapter make sure to select the option in the upper right hand corner "View in long strip mode"
Just go read it, go read it now.