I'm trying to keep a list of RPGs available on itch.io, but I'm not focusing only on what's not also available on Steam, and what I would recommend are games we talk about here, namely
Lurking and
Lurking II (must plays if you like open world exploration and keyword dialogs),
Bludgeons and Krakens (a single character, turn-based, open world game, with free character progression and an emphasis on fun combat),
Gates of Integrity (a Bard's Tale clone),
Towers of twilight (a big procedural RPG, with plenty of things to do and where your enemies also assault castles, combat is classic turn-based although' it's disturbing at first because basic attacks are automatically repeated),
Battle of esturia (a party-based, turn-based one).
Other possibility relevant games, either smaller games or games that I've not finished nor played enough to judge, could include
ASCII Dungeon (a classic crawler),
Shadow over the twelve lands (a crawler with pregenerated characters),
Myrkvidr (an Ultima thing made with RPG Maker),
Escape from greyrock (a classic RPG maker game but with important story choices),
Hollow (inspired by the japanese game Laplace's Demon),
The curse of svaltfen (an Ultima thing but I've not played it),
Minima and
Anteform (I've only played the first one, which is an Ultima thing),
Pioneers (an age of discovery RPG, which is on hold but let's hope the enthusiasm of the players will eventually make the guy work again on it),
Interstellar rising (a space CYOA-exploration game which crashes).
It's possibly the best place to find
Legerdemain (not exactly Ultima, not exactly a roguelike either although' in practice you definitely lose your save because you forgot to resave after reloading) and
FastCrawl (it's a game where you launch small games, it gives you a party and a small dungeon and let's go). Not sure about
Excelsior and
Excelsior II and about
Realms of Quest games (fourth one is there too, fifth is, I think, not).
Finally I like to shill for
Evowok Breeder, a pokemon kind of things so definitely not for everyone here but I think it's pretty good,
Cosmodog is a turn-based exploration game which I think is great but not really with RPG progression, and
RydenWood is another exploration game which is possibly vaguely relevant here but is not big on RPG progression either. Its sequel,
RydenWood : Deeper than before, that I have not played, seems to have replaced a handcrafted world with procedural ones.