What is it?
It's a moba, and instead of objectives like Dragon or Baron or Roshan or Runes they have quests that serve a similar purpose. If that makes sense to you, then you understand 90% of the game.
The other 10% is interesting, but the bottom line is that it has personality
and that is very compelling to me.
Audio: amazing voice acting, sfx and music
Visuals: bad graphics but very great art and design. It 'feels' good to interact with.
Lore: interesting writing, love the characters and actually want to learn more about them.
Character: the characters are dark and interesting, and there isn't so many that they are mostly just copies of one another.
Final Note: you cannot speak of mobas without considering the communities within them, typically the worst of humanity. Half my games have been fine or pleasant, the other half trashy, which among mobas... well, that's quite above average :)
edit: the trashy people are sort of bad at trolling, and the nice people are wonderful, so consider that :)