Welp, I'd say I had more fun reading the comments than reading this chapter.
It wasn't established at all why the MC cannot just, indeed, kill the king and princess. It wasn't made apparent at all why the MC revealed himself to the princess, and thus instigated the entire problem to begin with.
Idiot Plot galore, but isekai be isekai, it's not a bad direction as long as the MC stays away from the royalty (and vice-versa). A dungeon-based isekai still can provide a few chapters of browsing through.