Dungeon Defense, up front, IS a 'Travel to a new world/Trapped in a game" story, depending on how you look at it. Heavens knows there have been plenty of those in the last few years (including the one I'm writing, sadly). There are a few points which make this one stand out for me, however, and while I don't want to intrude on my Pros/Cons for later, I'll do a quick synopsis.
A cynical and horrible young man has just given up on life due to his upbringing, when he fills out a curious game survey sent to him online. Then, he wakes up as a Demon Lord in the middle of an attack. And not some run of the mill exceptional Demon Lord, but as Dantalian, the tutorial boss. Yeah, that's kind of a tough break. Being that he's a bit of a manipulative sociopath already, he sets out to make himself a place in the world through suavity, treachery, and cunning.
- Bad Guy - I'll be honest, I do love a plausibly written villain. I've always been negative on stories where the bad guy did evil things, just because 'they are the bad guy.' I want the antagonist to have a reason for what they are doing. Don't destroy the world just because. Dantalian is a villain, yes, but he's always moving toward achieving his aims, and he'll explain to you why he wants them. Further, unlike Ainz from Overlord, who is a generally amicable, if misunderstood fellow, Dantalian really is as bad as he seems. Maybe more than you think he is initially, even.
- Fun Characters - It's hard not to root for Lapis Lazuli, the half-breed Succubus who gets looked down upon by everyone around her. This series has a lot of other well thought out, multi-faceted characters, including vampires, demons, goblins, and even the occasional human. Some interesting interactions are explored as well between characters you wouldn't think of, including some relationships and alliances that make such intrinsic sense you are shocked you didn't think of it before.
- Culture Shock - Dungeon Defense is a Korean light novel, and not a Japanese one. While a habitual light novel reader will come into a series like this with a set of expectations, most light novels that have been translated to English come from Japan. Not to say there aren't exceptions, but many light novel protagonists are fairly wishy-washy, insecure, or dense (they even have a word for it, donkan, meaning a protagonist who is so dumb with women that they can't get laid even when a naked woman falls out of the sky and hits them). I am happy to let you know that Dungeon Defense is blessed with a protagonist of stern, resolute, decisiveness. He's like a Honey Badger. He takes what he wants.
- Should'a Seen This Coming - Given that Dantalian knows how the world ends, it is occasionally frustrating when he gets himself in a situation he should have foreseen. This is a minor problem, and perhaps a bit of quibbling, but given how he seems omniscient at times, even with things that would not have been in the game, when he's blindsided by something you find yourself shaking your head.
- Chekhov's Gun - You know the one. There was a gun on the wall in Act I, that means someone is getting shot in Act II. The foreshadowing in Dungeon Defense can be a little...heavy handed. I feel the impact of this problem is a bit diminished by the fact that *spoiler alert* Dantalian already knows everything, but it is there nonetheless. At several points in Volume I, Dantalian's inner monologue chucks out 'random' factoids, that become major plot points in a chapter or two.