Great choice — kingdom-building is one of the richest subgenres in web fiction right now. Here are my top picks: Crimson Regalia is a standout: a fallen noble rebuilding his house from nothing against a corrupt empire, with excellent political intrigue and slow-burn power accumulation. Reincarnated as the Last Noble takes a modern-knowledge-in-medieval-fantasy approach that feels fresh and grounded — the protagonist uses real historical strategy rather than cheat skills. The Regressed Demon Lord is Kind technically qualifies too, since the protagonist ends up building a domain whether he wants to or not, with comedy and action woven throughout. I'd also suggest checking out Dungeon Defense if you enjoy a darker take — it's technically dungeon management, but the political maneuvering between demon lords reads very much like kingdom-building.