I've read the LN up to the 5 Vol., I think, and there were at least a few more untranslated at the time. The manga is somewhat close to the LN until Mugen appears - nothing after that (with Mugen's existence included) was anywhere in the LN I've read. Instead, the LN focused on deeper worldbuilding for a while, included a few plot twists where the MC started thinking about the nature of the Dungeon, the world itself, and the relationships within, including his own. If you've played Bioshock, it was on the level of meeting Andrew Ryan and his "hit, would you kindly". The LN translation was dropped, and now I came back to see the manga being obviously axed, with the ending being completely divorced from the plotlines present in the LN. That's a lot of wasted potential here, in cases of both manga and LN
Also, what about Arifureta and copyright? It doesn't make any sense, at all: the characters are very different, the theme here is much darker and without annoying "comic relief" every other page, the worldbuilding is much more detailed and less cliche (or maybe I just like the cliches in DS better), and the plot is only similar for the first few chapters... And yeah, in the category of "got dumped/swindled/almost murdered by the classmates/god/king&nobles, miraculously survived and went on to get his/her revenge" Dungeon Seeker is actually really decent. Better than things like that guy who "healed the world and reversed time", or who started brainwashing and raping all the girls he could find, or who started getting extremely delusional and signed some "joint-revenge-venture" with a bunny girl, or is (
) who kills everything with a single word, etc...