I'll share two I recently found:
Wizardry Llylgamyn Saga (https://archive.org/details/wiz-ls-pc)
Sword Of Moonlight King's Field Making Tool (https://www.swordofmoonlight.net/) [haven't tested this yet on Win 10 but I think it works]
https://www.myabandonware.com/ for anyone who wants some free games that are in a legal grey area and you don't have to worry about the piracy police getting you.
I don't know if these are necessarily "hidden" gems, but Icewind Dale is a solid CRPG from 2000, there's also a remastered edition if you have a VPN.
https://www.myabandonware.com/game/icewind-dale-db4
https://1337x.to/torrent/2969875/Icewind-Dale-Enhanced-Edition-v2-5-PLAZA/
Also Arcanum: Of Steamworks and Magick Obscura, but I would recommend installing the unofficial patch because it is a Troika game and is such buggy as shit in the original state.
https://www.myabandonware.com/game/arcanum-of-steamworks-magick-obscura-csi
https://terra-arcanum.com/drog/uap.html
Two CRPG classics, thanks.