Created by Rob Anderson and originally released in 1991 for the Amiga (my first gaming love) and Moonstone was later ported over to DOS in 1992. If you're interested, GOG also did an interview with the creator. I have fond memories of it, playing both solo and in co-op with my brother, back then it was probably one of the goriest games we had and the real-time battles were great.
There's even an attempt to build an open source reimplementation of Moonstone up on GitHub, which looks like it could use some fresh coding help.
You can grab the classic Moonstone here, which GOG have nicely packaged up for Linux with DOSBox.
If real retro classics aren't your thing, do check out the big RPG sale on GOG too including some good stuff like:
- Halcyon 6: Lightspeed Edition - 80% off
- Shadowrun Trilogy - 75% off
- The Dwarves - 75% off
- Torment: Tides of Numenera - 70% off
- Fell Seal: Arbiter's Mark - 66% off
- Vaporum - 60% off
- Iratus: Lord of the Dead - 50% off
- Pillars of Eternity - 50% off
- Pillars of Eternity II: Deadfire - 50% off
- Tyranny - 50% off
- Hellpoint - 30% off