Another book with an age-gap romance, Ryoumin 0-nin Start no Henkyou Ryoushu-sama doesn’t end up as creepy as Reijou wa Ryuutei Heika o Kouryakuchuu (despite the much larger gap) primarily because the older of the two isn’t actively pursuing it. That issue aside the author seems to be interested in playing around a bit with character tropes, as the princess ends up hostile while the noble 2nd son with a harem turns out to be incredibly altruistic.
Not sure how far you can take a kingdom building series that features a relatively simple-minded protagonist who’s only skilled at combat though. Some sort of advisor will have to be introduced before long.
TurtleMe‘s first two The Beginning After the End novels greatly resemble the start of your average reincarnation isekai light novel. The main twist being that the protagonist is from an urban fantasy version of Earth where only people with exceptional combat ability are allowed to become the king of a nation. Anyway, the first book is perfectly fine if maybe a little rushed. The second though… the second has some issues.
Introducing a steam engine, kicking off an industrial revolution, somehow won’t majorly affect the world? And where exactly did the protagonist learn about the internal workings of steam engines or how to draw technical blueprints for that matter (he was a combat-obsessed orphan in his previous life)? The author seems to have completely lost sight of their own character. The confrontation with the king was also baffling and considering the next book is the start of an academy arc I do not think I’m going to follow it any further.