I know most of the Bethesda RPGs have massive mod support, and there’s games like Minecraft that have more mods than anyone can imagine. I would consider those games pretty playable in their vanilla states. Would you say there are any games that were “saved” by modding? Or that are still kept alive by thriving modding communities? What are some of your favorite mods?
Factorio has the best modding API and user experience out there.
Some mods are not possible due to no native code mods but the devs add things to the modding API for every reasonable request.