Nameless one
Wizzard
7,62 High Calibre
Fortune Summoners: Secret of the Elemental Stone
Puzzle Quest
Space Rangers HD: A War Apart
Din's Curse
Magical Diary
Child of Light
Transistor
Defender's Quest: Valley of the Forgotten
The Long Dark
Planet Stronghold
Terraria
E.Y.E: Devine Cybermancy
Spellforce 2: Faith in Destiny
Spellforce 2: Demons of the Past
7 Days to Die
Life is Feudal: Your Own
King's Bounty: Dark Side
Endless Legend
Puzzle Quest 2
RPGWatch Steam Curation List
here is my opinion about some of those games if you still want it since no one else posted.
Space rangers HD-Hell yes game is great
Din's curse-It's fun game with some interesting features but don't deserve recommendation imo.
Transistor-It has high points and some really good ideas but I don't think realized that well.If you are going to consider Supergiant game Bastion deserve it more.
Endless Legend-Good game but not RPG, there are also 4X games that desrve recommendation more.
Terraria-totaly not RPG
Long Dark-In very early stages, too early to say
Puzzle quest-it's very RPGish and it's good so yes it would spice things up.
Also consider FTL(this must be on the list imo) and Valdis story.