Back when I wrote the About.com website I created (curated!) a list of useful C libraries. You can still see if you look on archive.org, for instance this is it back in 2013 when I finished working on about.com.
Now that library was general stuff, not with a games (or loosely games related) like this site but many of the links still work. Back then most websites used http not https, so if a link doesn’t work, change the url to https and try it again. Some links will have ‘rotted’; its inevitable on the web (and I never miss a chance for a visual pun!) but all of it was open source so it probably has a higher chance of it still being around.
I will also be trying to salvage games/games related links from there and add them to my sites games links or C code links. For instance I found the CBM-64 BASIC and 6502 emulator in C by developer Michael Steil on GitHub and have added them to the C code links.