Here's some lists of PC games that were truly released by their creators as freeware (not abandonware/questionable/pirate).
https://www.pcgamingwiki.com/wiki/List_ ... ware_games
https://en.wikipedia.org/wiki/List_of_c ... s_freeware
https://rateyourmusic.com/list/Kaernk/f ... legally__/
I was on the official forums of a few of these when they were officially deemed freeware back in the day - OMF2097 & The PixelPainters games.
GOG hosts a bunch of them for free with their own compatibility fixes applied already. It's cool that they talked to each creator of these and officially re-released them with full permission. I dislike the DosBox options they choose by default for the DOS-based games, but usually someone will have some suggestions in the review/comments section to configure it better.
https://www.gog.com/en/partner/free_games
To tie the other topic together; I just scrolled through the Wikipedia list and I completely forgot that Lode Runner Online: The Mad Monks' Revenge was released as freeware. I bought it boxed (discount) in the late '90s and totally loved every minute I played of it. The music and graphics to me at the time really made the game "Pop": changing environments and high definition hand painted backgrounds!. Before that I was playing Lode Runner on NES on a pirate 100-in-1 Contra Function 16 Famicom cart with a "Honey Bee" 60-72 pin adapter. That and the DOS CGA version. If you've never played the remake before I suggest you give it a try - someone has rebuilt it from the ground up for multiple systems:
https://mmr.quarkrobot.com/
There is a whole pile of open-source PC games where the full source-code was released for free, tho most of those don't need any fixes because fans have re-compiled them to work on modern hardware already, but that list is mostly different than the above lists and has another incredible library of awesome games.