The Last Sovereign (NSFW) is an 18+ RPGmaker game. The basic premise is this: What if you had a setting with a bunch of hentai tropes lumped together and played straight, with no porn logic or stupid characters?
You play as a middle aged, very competent army veteran who gains the powers of an incubus, and reluctantly uses them with the aim of making the world a better place, slowly developing a harem of well realized, cool characters along the way. There's sex scenes, obviously, but you very quickly forget all about them as you are plunged into an underdog story where you have to manage your fledgling armies + resources and have to constantly make tough decisions.
If you're not excited about Brighter shores then I really don't know, for some reason no one else has ever tried to make the same type of game (aside from Genfanad and Titanreach, both of which have shut down quickly after release)
You could check out Project: Gorgon, it's something of a mix between Runescape's multitude of slow-to-level, interconnected skills on one character and a more typical MMO with distinct classes, buildcrafting and group content. It has a free demo on Steam. All of that said it's only vaguely similar, and I wouldn't mention it if there was anything closer to OSRS.